Slightly altered the layout of the SpikeDisplayEditor, also I changed the waveform line width from 1 to 2 pixels

Implemented basic panning and zooming for the stereotrode plots.  I was unable to hook up events from the SpikeDisplayEditor to the SpikeDisplayCanvas correct... so clicking in the 4 quadrants of the canvas has the effect of zooming/panning in/out

fixed drawing bug where the upper voltage grid line would get drawn outside the axes if the axes were resized too small

Polished up the SpikeDisplay Canvas UI. I added channel labels for each spike plot, additionally I re-enabled the labeling of the threshold in the individual WaveformPlots, this is using the FTPixmapFont objects like those found in OpenGLCanvas. This is in lieu of using Glut to render fonts.  The rendering code is in PlotUtils.cpp.

the SpikeDisplayCanvas now supports scrolling! i had to change OpenGLCanvas::showScrollBars() from private to protected. Additionally I made scroll pix protected although that might not be needed.

Fixed the ProjectionAxes class such projection plots persists after destruction and recreation of the projectionTexture. This event happens whenever the openGL context is destroyed or the projection plot size changes.

Additionally I fixed a minor bug that was preventing projections from getting plotted for tetrodes

this is _the_ commit before I start integrating the texture based rendering for projection plots

updated spike plotting to show points in the projection plots, points don't persists and I haven't been able to disable anti-aliasing on the mac so those things still need to be done

The SpikeDisplayNode object isn't working properly. Queueing of spikes there appeared to be what was causing the problem.

I need to consider an alternative way of handling the SpikeObjects. In the past I've used a circular buffer but that has
problems with having a set size. I can use an stl::queue but queues are not thread safe, which is something that we
definitely need.

Anyway the plots show up and dance when the viewer is turned on.  I still need to implement a Stereotrode plot and then the
tetrode plot. I'll probably derive them from the ElectrodePlot base class instead of creating a base classs from which all
three plot types are derived from.

Finally I need to get a better handle on the setup of the OpenGLCanvas and how its sized.  How the "Magical" scroll bars work
and how to auto place the plots.

Do we force all the plots to be of the same type? Or do we mix in Electrode Plots with Tetrode Plots?  If so how do we orient them all?

initial checkin of the SpikePlotting directory. This will contain all of the objects used  for drawing individual spikep plots