My changes for SublimeInsertUnicode

Hello.

I very like your sublime plugin and use it always. But when ST3 come, plugin seems not working as before because ST3 uses python3 as script language. For my purposes I rewrite it for python3 and add some changes:
* Files Blocks.txt and UnicodeData.txt are added to the repo. It's not changed last time and maybe won't change at all. But downloading this files require internet connection;
* I removed commented commands because never use it;
* `my_unichr(n)` function was removed because python3 doesn't have problem you described in comments;
Unfortunately I haven't work with python2 so it hasn't backward compatibility.
If you interested, we can rework it for publication in https://sublime.wbond.net.

With the best regards