Fix some compilation warnings
Extract edts-start-load
Load all el-files in plugin dirs
Add f.el submodule
Remove path-util submobule
Use f.el instead of path-util
Use f-traverse-upwards for edts-project-selector
Remove all submodules (yeehaaw!)
Add pkg-file
Complain if EDTS wasn't installed as a package
Load edts-start and compile erl-files at elisp compile-time