NameSpace support for FFI

- mTypeNames map is updated to keep fully qualified class name instead
of just class name as key.
- ClassDeclNode.Name for a CLRModuleType is compiled as fully qualified
name for the CLR type.
- ClassTable class is updated to maintain the class symbols in
NameSpace.SymbolTable
- ClassTable.IndexOf() operates on partial name as well and it can
return a unique index as long as given name can be resolved to a unique
symbol in the symbol table.
-Verified that there is no regression because of these changes.
Merge pull request #159 from sharadkjaiswal/Namespace

NameSpace support for FFI