Change float32/uint16 distinction to point/voxel distinction

[bergwerf]

Although float32 is the underlying type to store exact particle coordinates and uint16 is the underlying type to store voxel positions. It is more straightforward if all functions that are specialized to handle a specific type are named using this point/voxel distinction. Example: Domain.containsPoint and Domain.containsVoxel instead of Domain.containsFloat and Domain.containsUint16. The BromiumData.useIntegers boolean and related namings should be converted to useUint16.

[bergwerf]

This issue is no longer relevant due to #3