missing dependencies
use a more compact representation for size. This is not currently useful but may help reduce memory usage later
factor out mask access into a function so I can play with representations
Revert "use a more compact representation for size. This is not currently useful but may help reduce memory usage later"

This reverts commit e7033ec2b712be775434744089e4c5da2d9b1c6a.
Better documentation and slightly stronger requirements on intmap_combiner
change intersection behaviour to merge right for consistency. This would be a terribly rude thing to do if anyone actually used this library
smaller intersection ranges because that test is bloody slow
Add an is_subset_of function for, well, calculating if an intmap is a subset of another