Print a more appropriate message on 'rebar info'

generate-upgrade can now take target_dir argument

erlydtl implemented 'binary' option. Add new clause for {binary, false}.

Remove experimental flag from:
* qc compile_only=true
* eunit compile_only=true
* src/foo.app.src.script
* eunit tests=

Adapt rebar_erlydtl_compiler to handle warnings emitted by
erlydtl:compile/3.

While at it, update getopt.erl to git rev 78eda3b.

To avoid treating plugins' info/2 functions as commands, we catch calls
to 'rebar info'. Previously (4b8c81fb) we simply printed the help
string, but it's much more informative to print the following:
Command 'info' not understood or not applicable

inttest/rgen_1: double the timeout a second time

Clean up rebar.config.script

Added a library template.

bootstrap: avoid trying to run 'debug' command

rebar_dia_compiler: fix Dialyzer warnings

If you invoke 'make debug', then bootstrap executes rebar:main/1 with
the extra argument "debug" and rebar treats that as a command. There is
no such command.

Without this patch you will see the following on bootstrap:
Command 'debug' not understood or not applicable

60s still seems to be too low, as it timed out for at least the R15B01
job of the timeout patch merge:
https://travis-ci.org/rebar/rebar/builds/15051701
https://travis-ci.org/rebar/rebar/jobs/15051703

Fix log levels

inttest/rgen1: increase retest timeout (30s -> 60s)

The current default (30s) causes inttest/rgen1 to timeout too often. Add
retest.config to double the timeout.

Make list of commands (for unabbreviation) easier to maintain

It's easier to modify the list with each command on a separate line.
The shell completion scripts have already been modified that way.

Switch retest dep to upstream (dizzyd/retest.git)

Now that Dave has merged all patches, it's safe to switch back to
upstream retest.

rebar_core: fix Dialyzer warning introduced in aa46d85 (#157)

Fix false reporting of (plain) vsn strings

Add missing dep examples and fix existing ones

Fix erl_opts use

Previous generate-upgrade required renames in rel/ directory:

    rebar generate
    ...changing code...
    mv rel/<release> rel/<release_prev>
    rebar generate
    rebar generate-upgrade previous_release=<release_prev>

With the proposed changes you can now do the same without moving things:

    rebar generate # default target dir: rel/<release>
    ...changing code...
    rebar generate target_dir=<release_new>
    rebar generate-upgrade target_dir=<release_new> previous_release=<release>

Delete unused inttest/retest binary

Avoid getting erl_opts twice in test_compile/3, and make sure the
correctly filtered (platform_define, etc.) version is used.

rebar used to mistakenly report plain version strings like
{vsn, "1.0.0"} as follows:
DEBUG: vcs_vsn: Unknown VCS atom in vsn field: "1.0.0"

Properly detect unknown/unsupported version terms and abort
if we encounter one.

While at it, rename a variable in vcs_vsn/3 to be non-misleading.