Make script executable.
Remove dead code.
Make word_dictation_document.py either get or set the dictation buffer contents.

Previously, when run from the command line, it simply got the dictation buffer contents, which didn’t entirely fit its name.

Also add an explicit clear_contents function.
I know what I need to do to fix this, but it’s no longer necessary, so simply remove it.
A standalone script to clear the dictation buffer.