Reduce unnecessary use of smart pointers

Speed up type checking by using std::maps and switch statements
Add compile flag to win/IfcGeom.vcproj

src/ifcgeom/IfcRegisterConvertWire.h

@@ -1,6 +1,6 @@
 #include "IfcRegisterUndef.h"
 #define WIRE(T) \
-	if ( l->is(T::Class()) ) return convert(reinterpret_pointer_cast<IfcBaseClass,T>(l),r);
+	if ( l->is(T::Class()) ) return convert((T*)l,r);
 #include "IfcRegisterDef.h"
 
 #include "IfcRegister.h"