qtgui: adding a time raster plot (support for bits and floats).
qtgui: making sure all qtgui files have copyright notice.
qtgui: added time raster GRC block to the block tree.
qtgui: adding QA code for time raster plot.
qtgui: updated documentation in doxygen manual about qtgui plotters.
qtgui: fixed intensity bar for time raster plots.
qtgui: set default nconnections to 1 for time raster plots.