Signal Generator now generates fake action potentials!!! The phase dial can be used to scale up and down noise on the spikes

initial commit of SpikePlot.cpp and SpikePlot.h which define a general spike plotting object that can completely replace ElectrodePlot, TetrodePlot, StereotrodePlot. SpikePlot objects can be added to the canvas and render fine, however, eventually the Tetrode variant of the SpikePlot causes a segfault, probably due to the way that spikes are copied around in the SpikeDisplayCanvas.

Altered the default settings of SignalGeneratorEditor and SpikeDetectorEditor to reflect the desired values for debugging the spike viewers

fixed bug where the max size of a spikebuffer was 256 bytes, this is too small for tetrode spike, this value is not determined by a constant defined in SpikeObject.h

began porting code from stereotrode plot to tetrode plot. It shows up in the canvas and actually shows spikes after the display is panned or zoomed at least once. Although spikes only show up in 2 of the 3 waveform axes

fixed bug in SpikeDisplaCanvas that was preventing spikes from getting rendered. The variable samplePosition was created but not initialized. I set it to 0

Previously, traces for each channel could not overlap, meaning that
channels would appear to artificially saturate. There are now two
parameters that determine the location of an LFP channel: plotHeight
and interplotDistance. Thus, plots can remain close together while
keeping a large range.

In order to improve rendering efficiency, the screenBuffer was changed
from a Juce AudioSampleBuffer to an array of GLfloats. Instead of specifying
each individual vertex, OpenGL receives a glVertexPointer. Exact timing
improvements have not been measured, but they should be significant.

The IntanThread can report TTL events on its 6 input channels. This was tested
with an Arduino; input detection is fast and reliable.

The IntanThread also generates its own timestamps, allowing the software to move
toward a framework in which timestamps come from input sources, rather than
from the RecordNode.

Finally, an ArduinoOutput module was added, which allows the software to
communicate with an Arduino via serial output.