Don’t set __CF_USER_TEXT_ENCODING

This was previously required because the default encoding for pbcopy was MacRoman (on a Mac configured for the Western region), so we had to set this variable to make it UTF-8.

Fortunately recent versions of OS X have switched most things to UTF-8.
Remove code related to interactive input

We have kept the code to allow expert users to manually install the interactive input lib, but I don’t think it really works on 10.7 and up, which is the minimum requirement for TextMate, so no need to keep this code anymore.