tweak .gitignore to be more haskell-specific
add --ignore-encoding-errors flag to continue processing when file with non-utf8 encoding is encountered
fix treatment of type families
use tasty to organize tests, add tests for toplevel functions without signatures
rework sorting of tags, implement tags of toplevel functions - introduce new repeatable kinds of tags that later are resolved to single unique tag, fix tests
fix O(n^2) algorithm when merging sorted tags for individual files
disable tracking of tag prefixes when collecting vim-style tags
place tests unter tests/ directory, cleanup cabal file a bit
move main login into FastTags module, tweak cabal file to build library with it