Improved documentation
Removed all needless file for common branch
Added explicit files that must be kept
Added what I think are base bash files
 * Some file might be a bit of splitting for parts that may only work
   on msys2 or a machine specific. Will come later on.
Added what I think are base msys2 files
 * Some file might need a bit of splitting for parts that are machine
   machine specific. Will come later on.
Added new functions
 * I will try to think of way to refactor recongiure and toolchain so
   they are more generic and could fit in bash branch.
More stuff in readme
Merge branch 'common' into bash
Merge branch 'bash' into msys2