Change num lines to int in hatch.

Fixes numpy issues warnings
Index with an integer in test_axes
Number of verts in simplification is an int

Fixes numpy warnings in indexing
Explicite cast to int in colors
Cast steps to integer in cbook
Cast to integer in bezier for indexing
Cast to integer in contour

as suggested by comment
Integer division in mlab test
Integer division in trirefine
Remove redundant cast to int
Delay the cast to int in contour.py

This is to allow checking againt nan below
Thangs @argriffing
Merge pull request #3241 from jenshnielsen/numpy_clean_warnings

Cast to integer to get rid of numpy warning