Trim trailing/leading whitespace from command line.
Add extra space after completion.
Use 'using' instead of 'typedef'.
Beef up the bitvector interface.

We now have new block-related operations so that users can directly work with
the underlying blocks of the bitvector. This gives more control when using a
bitvector as building block for encoded bitstreams.
Begin the implementation of an EWAH bitstream.

This commit presents the first of a series implementing the Enhanced
Word-Aligned Hybrid (EWAH) encoding scheme by Daniel Lemire. It is a complete
re-implementation based only off the encoding format description in the paper.

The current implementation just supports appending bits, not yet (random)
access or bitwise operations.