Continuous Values CCL & Float/Double Support

You can now use cc3d on continuously valued raw data images to get a rough segmentation using the delta argument.

I also added float/double support for both discrete and continuous value operations.

Zenodo Release v1

Citeable release on Zenodo which includes several features:

• Multi-Label CCL
• Use of Row Foreground Transitions (RFT) to reduce memory usage.
• Foreground row finding pass for accelerating sparse objects.
• 26, 18, and 6 connected modes.
• Use of "Phantom Labels"
• Voxel Connectivity Graph generator.
• Region Graph
• Accelerated extraction of binary images.