ignore optional deps for now

add to end of code path not the beginning in handle_deps

Add support for an unlock command

Allows to remove entries from the lock file, or the lock file as a
whole.

Default deps always to the default profile

Mainly CT changes

When fetching dependencies for the first time using a profile (`rebar3
as prod release` or `rebar3 ct`), the dependencies get fetched into the
non-default profile. This has two consequences:

- the files get re-downloaded on follow-up runs
- the lock file includes incomplete or too many deps in its list

This patch forces dependencies in the default profile to be stored in
_build/default/lib even when running under other profiles, then symlinks
them to the correct one.

This makes it so common dependencies in 'default' be downloaded there
and avoids re-downloading them. Should also fix the lock issues.

include applications list in compile sort

Rename wtf->report, add all dep versions

Improve error handling in ct provider

support single atoms for pkg deps, fetch highest version available

Warn on bad use of include_lib but try to find the header anyway

disallow suites in project root

fixes #331

rm old beams, make erlcinfo graph per app isntad of global to project

merge rebar2's Refactor logic and optimizations in rebar_erlc_compiler:doterl_compile/4 #467

fix build instruction