All scipy imports in the library are now optional (need to test each of these changes)
Several examples still require scipy.
corrected import
colormap no longer requires scipy.interpolate
Added SRTTransform3D test, corrected fromMatrix bug
added test for solve3DTransform
PlotDataItem._fourierTransform now uses np.interp
Added pure-python implementation of scipy.ndimage.map_coordinates
Expanded capabilities of interpolateArray function to support broadcasting
Added pg.gaussianFilter, removed all dependency on gaussian_filter
Removed all dependencies on scipy.

Merge branch 'make_scipy_optional' into develop