VectorToRaster

Added VectorToRaster for creating RasterSources from vector data using IDW interpolation, Kernel Density, and rasterization.
Merge pull request #720 from lossyrob/0.9.0-RC4/updates

VectorToRaster
Renamed .convertType to .convert on RasterSource
Merge pull request #722 from lossyrob/0.9.0-RC4/updates

Renamed .convertType to .convert on RasterSource
Delete Combination.scala
Merge remote-tracking branch 'upstream/master' into ingestchanges