Move PSTH editor files to its own folder

Builds/Linux/Makefile

Builds/MacOSX/open-ephys.xcodeproj/project.pbxproj

Builds/VisualStudio2012/open-ephys.vcxproj

Builds/VisualStudio2012/open-ephys.vcxproj.filters

Builds/VisualStudio2013/open-ephys.sln

Builds/VisualStudio2013/open-ephys.vcxproj

Builds/VisualStudio2013/open-ephys.vcxproj.filters

Source/Processors/PSTH/PeriStimulusTimeHistogramEditor.cpp

Source/Processors/PSTH/PeriStimulusTimeHistogramEditor.h

Source/Processors/PSTH/PeriStimulusTimeHistogramNode.cpp

Source/Processors/SpikeSorter/SpikeSorter.cpp

Source/UI/EcubeDialogComponent.cpp

open-ephys.jucer