Don't free a font that hasn't been created
Don't clear glyphs if the face was never created.
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
Filter warnings in rcparams test.
Suppress some more warnings.

These are genuine too so we filter them
Catch warning thrown in Mollweide projection.

This happens when plotting tries to expand
the interval for ticks beyond the defined region and do np.arcsin(y/sqrt(2))
where y is larger that sqrt(2) since the original limites matches the allowed
interval.

And Improve warnings message to clarify that this is related to ticks only.

Also some PEP8 around the code that I changed.
Filter warnings with more selective np.errstate context
Remove redundant cast to int
Delay the cast to int in contour.py

This is to allow checking againt nan below
Thangs @argriffing
Catch warnings in tightlayout test.

These are warnings that are raised because tightlayout does not work
fully automatic on gridspec. However, the point of the test is doing
this with some manual help so this works as expected.
Add note about disabling warnings in test_rcparams
Add note to test_subplots