docs: Added LaTeX packages for better math docs
blocks: Nicer LaTeX docs for multiply_matrix
docs: updated build guide with more specific version information.
cmake: typo fix to -Os in GrBuildType comment.
qtgui: fixes a bug in the number sink to respect the update time.

Addresses issue #703.
qtgui: fixes a problem with the number sink when fed NaN or +/-inf.

Addresses issue #704.
Merge branch 'maint'