Testfixes

This will fix up some of the test infrastructure that has been broken for a few months. 

1. Enable throwntogether png output from gui binary with --preview=throwntogether option

1.1 Begin to unify "library/system info" code into PlatformUtils.h/.cc , eliminate duplicate code

2. Fix bug in resize-2d

3. Add proper "expected" files for resize and rands 

4. Get rid of a lot of unused code & scripts