Compiler Refactor

We have compiler constants defined in, but not related to DSASM namespace.  They are moved to the appropriate compiler namespace

1. Move compile pass constants from DSASM to
ProtoCore.Compiler.Associative and ProtoCore.Compiler.Imperative
namespaces
2.  Move accessspecifier constants from DSASM to
ProtoCore.Compiler.AccessSpecifier namespace

Requires no tests as there are no semantic changes

@ke-yu @lukechurch 
Hi @junmendoza , the change LGTM. But how about remove some namespace qualifiers? I've to scroll to the right to read all code on github or on visual studio. Two layers are OK, but over two personally I think it is too may. :-)

You may use ReSharper to help you find out all unncessary namespace qualifiers.