print and format error message for bad .app files and all bad configs

Show stacktrace to errors caught in rebar3 module.

only run clean hooks once

run hooks when building plugins

don't lose global plugin providers

Properly setup namespace for dependency provider hooks

make deps task listed in help and update zsh/bash completions

add Windows build badge

Update deps if their checkout doesn't match lock entry

Lock forwarding is what happens when the file on disk are on a different
version from what is specified in the lock file. Files on disk should be
updated to respect what's in the lock file.

A negative test has been added so that lock files that are outdated vis.
the underlying git and packages but match files on disk do not get
forwarded. This job is left to the `upgrade' command.

Run hooks for single application only once.

don't add `{extra_src_dirs, ["test"]}` to `test` profile

adding it results in ct test suites being compiled before they're
properly copied so changes made to suites between runs are not
reflected if a run fails before test dirs are copied

Properly initialize command parsed args in rebar state

methods for retrieving `src_dirs` and `extra_src_dirs`

update readme building instructions to prefer source

purge loaded code when it conflicts with project apps in tests

note that now ALL `src_dirs` across included profiles are
compiled. previously only the last included profile's `src_dirs`
were used

install plugins from the global config to ~/.cache/plugins

update relx version. fixes #434

io_lib:format/2 will throw badarg when trying to print rebar_resource…

Ignore the build directory

generalize the "test" special dir into an {extra_src_dirs, [...]} option