better command line interface (cmdargs) and bump HSE version

Hi,

To generate tags for a good fraction of the files in `ghc/compiler` I need additional options implemented in this commit:

    hothasktags -I$PWD/stage2 -c --strip -XCPP -XBangPatterns -XScopedTypeVariables `find -name '*.hs'` >! tag

There are still many files that don't parse, but fixing those would involve changing haskell-src-exts I think.

Also mixed in with this commit is a bump in the version of haskell-src-exts required. Only versions >= 1.14 are supported now.