Revert "add row styling, fix get_cell_value bound error, add xor support"

This reverts commit 85bedad2fa815d82d401667c9b35f779377bdafa.

Conflicts:
	README.md
	pyexcelerate/Fill.py
	pyexcelerate/Font.py
	pyexcelerate/Format.py
	pyexcelerate/Style.py
	pyexcelerate/tests/test_Style.py