Add build environment for 'setup-config' file
Only call gvimdiff on files having changes
Allow Cabal 1.20 and update tests (1.20 changed the formating of the cabal file)
Remove unneeded 'test.cabal'
Reformat cabal file
Change the behaviour for updating only the lower or upper bounds

When now updating the lower bound the present upper bound is kept
if possible, it's only removed if the new lower bound is >= the
current upper bound.

If only the upper bound is updated, then no lower bound is added,
only a present lower bound is kept.

Thanks to Benno Fünfstück for these changes.
Add files of 'setup-config' build environment to cabal file
cabal-bounds 0.4
Merge branch 'master' of github.com:dan-t/cabal-bounds

Conflicts:
	lib/CabalBounds/Update.hs