* Remove more usage of mcs across the build and tests
* Fix -o[ut] mcs/csc argument difference
* Fix OpenTK.[dll.mdb|pdb]
* Complete some MCS|CSC renames
* Fix SYSTEM_CSC not to have a default option since it's not usable that way in every case (and most of them already deal with that option)
* Do not rename a variable used by mono itself
* Un-renamed two other variables
* Fix copying pdb
* Generate debug symbols for *.BindingAttributes.dll and copy .mdb for the old XamMac binary version
* Newer csc-compiled XamMac.BindingAttributes.dll have .pdb while the old, mcs-compiled binary cached, version has a .mdb
* Fix msc -> mcs typo.