Complete full lines. Fix #26

Didn't test neocomplete or `<C-x><C-u>`, but I hope this saves you 80% of the work.
`sh tmuxwords.sh -l ^foo -a ''` would fail *anyway* with the current implementation. (To search for the literal `-l` one would need to do `sh tmuxwords.sh '\-l' ^foo -a ''`). So this is not ambiguous.