Homework 4
Merge branch 'master' of https://github.com/rahlk/sbse
1. MaxWalkSat fixed.
2. xtiles encorporated.
3. 2 more models added, 1. ZDT3 and 2. Viennet3

Conflicts:
	hw3/models.pyc
	hw3/optimizer.py
	hw3/searcher.py
	hw3/searcher.pyc