Add xrange (=range) to py3 compatibility list
Revert back xrange's after merge of PR #2318
xrange([0-9]) and xrange([0-9], [0-9]) -> range
Add imports xrange from sympy.core.compatibility
Merge pull request #2336 from skirpichev/fix-xrange-regression

Fix regressions, related to xrange -> range conversion in PR #2318