This is mostly Bluewall's work but I am also bumping the general version number
OpenSimulator 0.7.5 remains in the release candidate stage.
I'm doing this because master is significantly adding things that will not be in 0.7.5
This update should not cause issues with existing external binary DLLs because our DLLs do not have strong names
and so the exact version match requirement is not in force.
* Cleaned up copyright notices in AssemblyInfo.cs's
* Added Copyright headers to a bunch of files missing them
* Replaced several common string instances with a static constant to prevent reallocation of the same strings thousands of times. "" -> String.Empty is the first such candidate.