First stab at new PP system
Allow base 4.5.*
Merge branch 'master' into new-pp-system
Loads more stuff for new PP system. Still broken.

locateAssetsReverse seems to work, at least
It builds now, at least
update pp spec
Make it buildable
Switch to a single source directory
Fix typo
Add getFilesRecursive and partitionM
unbroke (partially)
Remove unused tests
Fix all the tests
Add tests for scss/sass