Fix del before definition in nested loops with return statements
- Fix int ** int to return int (not float)
- Implement pow(x, y)
Fix #506
Cleanup
Merge pull request #746 from sklam/fix506

Fix #506
Merge pull request #745 from sklam/fix707

Implement pow(x, y) and related fixes
Merge branch 'master' into gpuarray_stream_binding