code cleanup

[claus]

The script code is the result of long-term growth, and it shows (code duplication, multiple approaches to commandline menues in different places, support for old versions of ghc/vim, ..). A cleanup would help to simplify/enable further development.

Apart from the issue of time (funds, anyone?-), what is keeping me from doing this is lack of access to suitable ghc/vim installations on multiple platforms. I've found it all too easy to make innocent looking changes that continue working on my configuration, but somehow manage to break someone else's.