Add API for a R/W of a BitSet (array of booleans)

[mhseiden]

As it stands, each single boolean value requires a full byte in the backing array; this is not very compact and could be addressed by adding a BITSET (boolean array) function. It could easily pack many boolean values into a single byte, by writing the # of bits in the set and writing each with the appropriate mask. This could be implemented in client code easily, but it would make sense to have a single, well tested API for this module that serves this function.

[dcodeIO]

Now merged!