CPSM like similar file bounce

When input query is empty, sort candidates based on levenshtein distance from the current file; Also do not show current file.
This makes bouncing between similar files (.h/.cpp) or (xxx.py/xxx_test.py) really convenient.

PS: I build windows and linux binaries. Mac binary is donated by a contributor.
If you'd rather not run these binaries, then just build it from source - it's easy.