Watch the target directory on compilation
Remove deprecations pre 0.10.0
Support for multiple callbacks in parallel compiler
Support each_module callback on ParallelCompiler
Initial work on ManifestCompiler that tracks dependencies in the manifest for quick compilation
Improve ManifestCompiler to track more dependencies
Put old beam files back if compilation fails
Just preload files if something is stale
Also record aliases as dependencies
Ensure no duplicate keys in the compile.elixir manifest
Simplify translate_apply
Merge branch 'jv-watch-manifest'

This brings smart compilation to mix compile, where
we only recompile files that changed and their dependencies.