Added basic automated testing capability, based on the MonKey Test (keytest.py) by...

Added basic automated testing capability, based on the MonKey Test (keytest.py) by McCabe-Dansted.
As of now, I plan to add a few regression tests for the Advanced Find & Replace using this engine.
It can be used for automated testing of other LyX subsystems as well. Just write your own *-in.txt
scripts and add them into the autotests/ folder.

TODOs:
- perhaps simplify keytest.py
- check how this behaves under various types of failure of the test
  (e.g., LyX crashing, hanging, ...) just to be sure it goes on with
  the other tests anyway.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@37364 a592a061-630c-0410-9148-cb99ea01b6c8