Set LC_CTYPE="C" when calling (unix) sort

For some non-ASCII characters we get an error from /usr/bin/sort stating that we have an “illegal byte sequence”. Since the system lack proper collation info for non-ASCII characters, forcing "C" as the character type/locale is only a loss for people who have installed a replacement sort command (or collation info).

Closes #12
Include “Randomize Lines” in the sort menu (bound to F5)