modules: added precompile (a zrecompile like function)

A litte helper/module to (re)compile zsh functions/scripts found in fpath
to speed loading and execution (p-as-prezto-recompile).

It can append element.zwc in fpath instead of leaving element directory if -f|--fpath-append is passed to it via command line or ':prezto:module:precompile' options '-f'.

Cheers.