Automatically select word under cursor if selection is empty.

Most of the time I'm just converting a single word to ASCII, but I must select the word first in order to run the convert command, which is a little annoying, so I made a little tweak:
* If something is selected -> convert the selection (the current behavior)
* if nothing is selected...
    * if the cursor is on nothing -> do nothing (the current behavior)
    * if the cursor is on a word -> select the word and convert it (added behavior)
As long as this doesn't break any current behavior, just added a new 'convenient' one, so I think it can be merged safely without confusing users.
Let me know if there is something I'm missing.