Cleanup and Tweak Visual Studio 2010 Projects

Remove the /vd2 compilation option, as it is no longer necessary[1], and
generate debug info (.pdb files, with little to no performance deficit),
to ease debugging release builds.

	* MSVC_Net2010/glibmm.vcxproj:
	* MSVC_Net2010/giomm.vcxproj: Remove /vd2 build option from the
	  builds, and generate .pdb files for release builds as well.

[1]: http://msdn.microsoft.com/en-us/library/7sf3txa8%28v=vs.100%29.aspx