There was a case where the Bitmap iterator logic could skip over a bit in a run
container if 1. the run container was not the first container in the bitmap, and
2. The first run in the run container had only one bit.
The bug was due to how the iterator was initialized with iterator.Seek(0) which
sets up the initial values of itr.i,j,k based on the type of the first
container. It was failing to set itr.k to -1 unless the first container was an
RLE container. itr.k is only used by RLE containers in the iterator, and must be
set to -1 when an RLE container is encountered. When Iterator.Next() encountered
the run container and itr.k was set to 0, it checked to see if itr.k <= run.last
- run.first, and if so it assumes that it was finished with the run and moved to
the next one. run.last - run.first is 0 in the case of a single bit run, so that
bit was skipped. After this, itr.k is set to -1 and all further iteration
proceeds as expected.
