Cleanup: Migrated GPU_VERTICES_PER_BLOCK and BYTES_PER_VEC4 to class
GPU.
Replaced usage of int literal with GPU_VERTICES_PER_BLOCK in
LineSegmentWindow.
Cleanup.
Cleanup, added javadoc markup.
Switched PAGE_SIZE_BYTES assignment from literal to dependent on
BYTES_PER_VEC4 and GPU_VERTICES_PER_BLOCK and added toString() in
PagedByteBuffer.