C# port of Mibble SNMP MIB Parser

This is currently a direct port of java library mibble 2.9.3 from http://www.mibble.org/ released under GPL2.

The original mibble code is pre-generics java, so I am attempting to update to current practices as I go.

As of the initial commit, the code compiles and executes, but there is lots of cleanup needed both in the code and the associated comments