v0.16 - Pandoras Box

Switched to a custom pflag fork with adaptions for non-posix variants like long shorthands (e.g. -shorthand).

So far this has been done by patching os.Args which was rather hacky. Modifications to the flag parser are quite complex though, so there might be some issues.

see #1293

Spec files support non-posix flags now as well:

flags:
  -np: non-posix shorthand
  -np, -nonposix:  non-posix shorthand and longhand
  -np, --nonposix: non-posix shorthand mixed with posix longhand