used to miss one sample/pixel, leaving small gaps occasionally

still needs significant performance optimization.
I’ll make a blog post about the details of why this approach should be
reasonable soon.

2do:
- debug, i’m pretty sure this is still missing one sample per pixel
somewhere, and the scaling form sample/histogram density to pixel color
is very hack-y
- performance
- make configurable via sliders

Conflicts:
	.gitignore
	Builds/Linux/Makefile
	Builds/MacOSX/open-ephys.xcodeproj/project.pbxproj
	Builds/VisualStudio2013/open-ephys.vcxproj
	Builds/VisualStudio2013/open-ephys.vcxproj.filters
	Source/CoreServices.h
	Source/Processors/PSTH/PeriStimulusTimeHistogramEditor.cpp

Conflicts:
	Source/Processors/DataThreads/RHD2000Thread.cpp

Fixed the value of bufferIndex, line 173 and following, as previous v…

Fixed the value of bufferIndex, line 173 and following, as previous version caused buffer index to be negative, triggering an assert, and most likely access violations and crashes. The important point is that in C99 the '%' operator is a 'remainder' and not a 'modulo' operator, so counterintuitively enough, it will give a negative results for negative numerators...