Fixes

Add missing clean/2

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.

app_bin option was used by the install command which has been
removed in 51ed787.

- Add 'escriptize' command
- Remove variable 'dump_spec'

Rename rebar_core functions for improved readability.
Remove redundant comments and blank lines.

Fix rebar.config.sample

Restore support for so_name, port_envs and port_sources

Fix rebar_erlydtl_compiler:erlydtl_opts/1 and rebar:run/2

Fix erlydtl dependency check

Erlydtl compiler

zsh completion: fix typos

Add skip_deps=AppListSeparatedByCommas feature.

I agree it's a bit of a weird thing, but it's a reasonable and safe extension. When time comes to properly overhaul stuff, skip_deps should disappear entirely.

Add zsh completion script

This allows `rebar ct suites=abc` to consider all suites when
you have a rebar setup with multiple sub_dirs.

Previously, rebar halted after it could not find the suite in the
first dir. But the suite might be present in another dir (when
sub_dirs contains multiple dirs).

This commit makes it so instead of halting, it prints a warning and
continues with looking for the suite in the other `sub_dir`s.

Note -- This uses try/catch to cause the test to be skipped because
otherwise I needed to adjust the return values of 4 functions, the
code path is pretty deeply nested here. Otherwise the whole call chain
needed to be adjusted for this return value:

`run_test -> make_cmd -> get_suites -> find_suite_path`

IMHO, I think for exceptional cases like this it is fine to use throw;
specially since only the {skip} is catched and nothing else.

For enable to shell-completion in zsh.