ENH: Output cast in SingleValuedCostFunctionImageSource.

Make sure to cast to the output image pixel type.
Merge pull request #226 from thewtex/costfunctionimage-cast

ENH: Output cast in SingleValuedCostFunctionImageSource.
BUG: Add GradientBasedAngleOfIncidence baselines for 32-bit MSVC.

Slight numerical differences.
Merge pull request #227 from thewtex/win32-angle-of-incidence

BUG: Add GradientBasedAngleOfIncidence baselines for 32-bit MSVC.