Some changes to improve clarity of code.
Support for reading and writing a range of samples at a time.
Add a size attribute, an optional sample array which stores application-specific dimensional size values.
Add convenience category for performing rectangle-based read and write operations on bit arrays.
Add new header for common functions, moved from BASparseArray.h
Add custom equality test method.
Cache value of derived count property.
Implement custom equality testing method.
Change some variables and return values to support negative values.

Counts might decrease and mutation methods might return a negative count delta, even though total count can never be less than zero.
Try a more legible format for description.
Fix issue in -isEqualToBitArray when checking equality of size.
Update to use explicit equality testing using custom methods.
Add new test for subArray.