Rather than just have a single Refresh method that gets called whenever
something happens that could possibly be of interest to the visual
tools, add seperate methods for signaling frame number changes and
changes to the file, and use the new SelectionController stuff for other
things that used to merit a Refresh. This eliminates a large amount of
redundant reparsing of lines which happened on paint, as well as a large
number of redundant repaints.
Frame data is now only uploaded to the video card when the frame number changes
rather than when anything at all changes, slightly improving performance when
using mesa's software opengl implementation.
Vector clip and drag tools now do a slightly better job of not
discarding the user's selection for no apparent reason, and strange
selection behavior from clicking on visual features should now be
entirely fixed.
Everything but the constructor and toolbar event handler in the visual
tool implementations are now private.
Originally committed to SVN as r4631.
5588cda268