This allows us to use `rebar_base_compiler:ok_tuple/3` and
`rebar_base_compiler:error_tuple/5` when returning from
`rebar_erlydtl_compiler`.

Use alternative way to detect net_kernel:stop/0 has succeeded as
suggested by Ulf Wiger.

The call to the grep program in rebar_ct:check_log/3 used single
quotation marks around the strings grep should search for. This works
well in most cases but fails on Windows 7 using GNU grep 2.5.4 as
installed by the Chocolatey package GnuWin 0.6.3.1 with the follow
message:

ERROR: cmd /q /c grep -e 'TEST COMPLETE' -e '{error,make_failed}'
ct/raw.log
failed with error: 2 and output:
grep: COMPLETE': No such file or directory

This commit changes the single quotation marks to double quotation
marks. I've tested this using GNU grep 2.5.3 on a Debian Linux machine
and it works well.

This ensures that deps of deps are updated AFTER the dep listing them
is, so that a complicated project with many layers of deps will be
updated correctly. Any new deps encountered along the way are also
cloned, and THEIR deps are also evaluated.

Also added was conflict detection, if a dep has differing versions or
source information, inherited from different places, that will be logged
at the end of update-deps, along with the origin of each conflicting
dep.

Previously, the configuration setting 'mib_opts' in rebar.config
would affect the call to snmpc:compile/2, so that (for example)
verbosity could be controlled.  However, the subsequent call to
snmpc:mib_to_hrl/1 did not include any of these options, so it
did not appear to be possible to control the verbosity of the
process of converting a MIB to a .hrl file.  To make matters
worse, the default was to dump a full trace -- including debug
output and various logging -- so the act of compiling a large
number of MIBs could result in a huge amount of "noisy" output
that hid any signal (meaningful warnings, errors, etc.).

This commit addresses that issue by replacing the call to
snmpc:mib_to_hrl/1 with a call to snmpc:mib_to_hrl/3 instead,
which includes an "options" argument that, at present, is only
capable of setting verbosity.  The verbosity setting is taken
from the 'mib_opts' setting in rebar_config, if present, and
the approriate kind of argument is passed to snmpc:mib_to_hrl/3.

It should be noted that snmpc:mib_to_hrl/3 is not listed in
Erlang's documentation, but does appear in the list of "API"
exports at the top of snmpc.erl in R15B01 (and remains that way
in R16B01), so this appears to be more of a documentation oversight
than the use of a deep, dark function call that was not intended
to be public.  snmpc:mib_to_hrl/3 accepts an #options{} record
(defined in lib/srdlib/include/erl_compile.hrl within Erlang's
source distribution), though most of the fields in that record
are ignored by snmpc:mib_to_hrl/3; only verbosity can be controlled
this way.

- restore support for "rebar help xref"
- update rebar.config.sample
- update 'help xref' string
- simplify new/changed functions by breaking out code or
  using simpler syntax where applicable

- refactor plugin dirs code to be simpler and easier to read
- use erlang-mode's default (%%) comments for portability/consistency
- make sure erlang-mode's indenter is used so that a future whole
  buffer indent doesn't get messed up

Also fix a single line exceeding max column.

The external deps_dir should have higher priority because
it is used by scripts and other build tools to set up the
location of the dependencies. This commit ensures that,
even if a project has set deps_dir in its config file has
lower preference than the command line one.

If a plugin is in a dependency, rebar didn't search for it carefully
enough.

REBAR_DEPS_DIR is often needed when a nif needs to be linked with a raw
dependency.

Since R15B02, ct_run returns a non-zero exit code when some tests
failed or were auto-skipped. (See ticket OTP-9865.)

This fix makes it so a non-0 code doesn't cause an instant failure, but
still prompts for log verification before doing so. Given the behaviour
was acceptable for pre-R15B02, it should be valid with it with
post-R15B02.

The fix should also be backwards compatible.

rebar throws away some error messages, e.g. the ones generated if the yecc compiler is broken.

This allows overlay_vars to merge comma delimited var config files

This commit add support for reading mustache 'lists' from files, so you
can use the list section functionality when templating things.

An example of the list syntax is as follows:

{package_commands, {list, [[{name, "riak"}], [{name, "riak-admin"}], [{name, "search-cmd"}]]}}.

Then you can, for each of the list elements, render some text:

{{#package_commands}}
chmod +x bin/{{name}}
{{/package_commands}}

* Allow the following predefined analyses :
   undefined_function_calls, undefined_functions, locals_not_used,
   exports_not_used, deprecated_function_calls, deprecated_functions

* Trap some possible errors in case module information is not
    available

* ignore_xref works on all checks and can take {M,F,A} tuples.
  (Automatic behaviour export suppression still only works on
  exports_not_used)

* allow plugins to print help message for implemented commands
* append core rebar.config options to common 'rebar help' message

One could argue that rebar_eunit does some pretty dangerous stuff when
trying to clean up after a test run, but specifically, it tells the
Application Controller to delete everything returned by
application:get_all_env(App). Unfortunately, included_applications
also goes, which can lead to a crash in application_controller, if
the application is subsequently unloaded.

This patch attempts the smallest possible fix: remove all env
variables except included_applications.

- added missing doctype
- added encoding statement
- removed invalid additional opening <body> tag

`systools:make_relup/4` fails with `{missing_param, registered}`
without a `registered` value.

The results returned by os:getenv() may contain unicode characters.
That said, we need to explicitly allow unicode when splitting the
environment information, otherwise badarg will be raised causing all
rebar commands to fail until the environment variable is removed.

Normally, Rebar runs eunit tests in the order the beam files are
stored in the file system (see rebar_utils:beams).  However, sometimes
it is desirable to run the tests in a different order (e.g. to
reproduce an error found on a build server).  For that case, it would
make sense to use the 'suites' parameter not just for selecting which
modules to consider, but also for choosing the order.