Update addition.py: s/stop/N
s/pyeda/pyeda.__name__
Add make.bat for Windows Sphinx build
Add eight queens puzzle document
Replace assertions with ValueError exceptions
Only use get_dual method for Or/And
Lint cleanup
Cleanup unicode operator strings
Fix small issue with Unequal.simplify
Add Nor, Nand as secondary Expression operators

Implement issue #44
Add some nor/nand unit tests
Use Nor/Nand in Equal/Unequal simplify