VS throws errors in several locations about ambigious type casting.
Fixed by removing the ambiguities and casting things to double.

Fixed spike detector crash

This fixes a segfault that happened when no electrode was selected on a spike detector (e.g., with no electrodes added); getSelectedItemIndex returns -1 in this case, which was causing an array bounds segfault in drawElectrodeButtons.

Conflicts:
	Builds/VisualStudio2012/open-ephys.vcxproj
	Builds/VisualStudio2012/open-ephys.vcxproj.filters
	Source/Processors/DataThreads/FPGAThread.cpp
	Source/Processors/ProcessorGraph.cpp

updated the project build configs to include the SpikePlot.cpp and .h files and exclude the previous plotters

updated the SignalGenerator to generate spikes of varying amplitudes and at a lower rate. Minor incremental changes were made to other files

changed the way that the SpikeDisplayCanvas lays out its children plots. It uses a more dynamic approach that allows plots of mixed types to be layed out in a (sort of) clean manner.

Also fixed various bugs

removed old plotting files (Tetrode, Stereotrode, Electrode) plots. They have all be replaced with SpikePlot.{h,cpp}