contributors -> maintaiers in template app data

hex.pm is now using maintainers instead of contributors in metadata.
Templates should be updated to reflect it.

Allow bootstrap to pick up existing Hex cache and deps

allow ct suites to be specified at root of project (or root of app)

convert ~> versions to highest matching

Bump cth_readable to 1.1.1

This fixes a typo that could cause failure in some test runs.

Upgrade relx to v3.11.0

This detects existence of Hex registry at
$HOME/.cache/rebar3/hex/default/registry and skips "rebar3 update" step.
It also detect presence of bootstrap dependencies in _build/default/lib/
and skips fetching them.

Plugin templates

this allows repeated test suite names across apps without conflicts

previously rebar3 dropped suites declared at the root of the project (via
`--suite=whatever_SUITE' probably) and warned. this was because the compiler
would recursively copy and compile everything in the directory indicated by
the test suite. this changes the copy mechanism to only copy erl source files
and directories that end with `_SUITE_data' into the `extras' dir in `_build'

This lets a plugin define templates to be loaded:

    $ rebar3 new
    ...
    proper (plugin): A basic PropEr suite for an OTP application
    ...
    $ rebar3 new help proper
    proper:
            plugin template (...)
            Description: A basic PropEr suite for an OTP application
            Variables:
                    name="suite" (...)
                    ...
    → rebar3 new proper fakesuite
    ===> Writing test/prop_fakesuite.erl

In this case, proper is a fake template file I've put by hand in
_build/default/plugins/rebar3_proper/priv/<somename>/, meaning it will
only work as far as it's called from the project's root.

The priority order of plugins is now .config > plugin > built-in, such
that someone could ensure plugins do not crush their own private
templates, but also that custom or plugin templates do overtake built-in
ones. It used to be Built-in > .config only.

Templates are searched for recursively in the priv/ directory of
plugins.

support temporary cdn change with HEX_CDN os var

Fix wrong relative path resolution

A bad template index does not crash; shows warning

Tests both absolutes and relative paths.

Add support for total code coverage

This should fix #955

The test is implicit as a bad index previously silently crashed rebar3.
By adding the bad index to the `new` suite's files, we can show that
things keep running.

symlink mib hrl output in apps `include' directories

upgrade certifi to latest release

this restores compatibility with rebar2 and erlang.mk

fix tupple merging for realsies.

Full rewrite, code should be understandable now.

Tup merge tests

- proper segregation of comparison between tuple terms and non-tuple
  terms. Guards weren't specific enough and that meant the wrong clauses
  of guards would be triggered
- proper deduplication of entries in the list. An additional N passes
  are required (we co-opt the reverse step to be more efficient) because
  while the original lists:umerge easily removes dupes, this is
  requiring more logic here since `[a,{a,b},{a,b,c},a,{a,b,c}]` is a
  possible interleaving and we'd want `[a,{a,b},{a,b,c}]` -- comparison
  of direct neighbours isn't enough.

(the tests fail)

Fix a small bug in the MIB compiler when building dependencies

Default to no eunit formatter if verbose specified

The previous default meant that verbose output would not be emitted.

fetch eunit_formatters config not from the command args but from the config

When compiling a dependency with a MIB file the generated hrl file is left in
the root project directory in a file called "include". This has the perverse
effect of messing up the search path for include files causing any dependencies
with files in their "include" directory to fail to build after that.

auto-update the registry if a pkg isn't found, fail if it still isn't found

remove backward_compat entry from travis s3