Move toDt and related methods to their own file.
Move toObjFile and related methods to their own file.
Move implementation of attrib related code to its own file.
Move implementation of argtypes related code to its own file.
Move implementation of PragmaDeclaration related code to its own file.
Move implementation of class semantic related code to its own file.
Move implementation of expressions semantic related code to its own file.
Move implementation of FuncDeclaration related code to its own file.
Move implementation of toObjFile for FuncDeclaration to its own file.
Move implementation of toObjFile for ClassDeclaration to its own file.
Move implementation of cast related code to its own file.
Move implementation of cppmange related code to its own file.
Move implementation of dsymbol related code to its own file.
Move implementation of e2ir related code to its own file.
Move implementation of toElem to its own file.
Move implementation of getRightThis to its own file.
Move implementation of toCBuffer to its own file.
Move implementation of genobjfile to its own file.
Move implementation of inline for ObjcSelectorExp to its own file.
Move implementation of interpret for ObjcSelectorExp to its own file.