Heavy refactoring of Codec/CodecDescriptor
Also lots of fixes and updates to UserpReader/writer
Updated the test cases, and serialization of type definitions is getting close
Completely redid the UserpType.equals() system, and now it "just works".
Fixed a bug in getBitLength for value of 0, and removed an unused function
Moved value-conversion code from UserpReader to ValRegister
Rearranged the CodecOverride system so it works more intuitively, debugged the type serialization, and wrote test cases for it
Updated the project file