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

Remove global plugins

install dep plugins & run provider hooks the same as shell hooks (Rereopen 316)

Fix ns help

modify `ct` provider to copy selected directories and compile them

alongside their source (ie, if `some_tests` is a directory that
contains test suites beams resulting from compiling them will be
placed in `some_tests` in the appropriate `_build` directory

update the dir used for upgrade deps to the new path under _build

impl shell completion

main module of a plugin just has to export init/1

Support namespace resolution in 'do' provider

cover enhancements

Fixes #306: help text consistency

fix clean all to use proper deps dir

re-export functions only used within rebar_utils that are also needed by...