Ignore Cargo.lock.
added word stemming support, closes #5

instead of failing, just disallow non-ascii input
this is already the case, we assume ascii already.

make stemming its own function

fixed weird whitespace, condensed stem-function
Merge branch 'master' of https://github.com/sinistersnare/spellck into stemming
Merge branch 'stemming' of https://github.com/sinistersnare/spellck into stemming