Exclude the .git directory from Doxygen generation
Add the plugin namespaces
Fix some doxygen issues/other minor tidying
Allow us to override the string set max lengths for some of the E1.37-2 functionality
Switch everything to use Constants.h rather than BaseTypes.h
Ignore some more doxygen temp files
Fix some comments
Merge pull request #463 from peternewman/e1.37-2

Various tidying up
Merge branch 'master' of https://github.com/OpenLightingProject/ola into trivial-fixes