Get Isle building on MinGW32 (#63)

* Add MxUnknown100dc6b0::~MxUnknown100dc6b0 stub

* Declare destructor of MxOmni and MxTransitionManager in class

* inline attribute must go first

* Stub LegoState::Vtable0x14 for Act3State

* MxStreamer::VTable0x14 is not an override

* Stub MxEntity::Destroy for LegoState::Destroy

* Stub MxUnknown100dc6e0 for MxSoundManager

* ::ClassName and ::IsA are const methods

* methods in the class body don't need a namespace

* MxSoundManager subclasses MxUnknown100dc6e0

* LegoInputManager subclasses MxPresenter

* NotificationId is an enum, and does not need __declspec(dllexport)

* Fix final #endif of legoomni.h and mxobjectfactory.h

* Add const alternative for LegoOmni::Create and MxVideoParam, only available for MinGW

* Alternative approach to MinGW compatibility

* MinGW on Linux is case sensitve

* Don't delete a member variable. C++ automatically destructs member variables

---------

Co-authored-by: MattKC <34096995+itsmattkc@users.noreply.github.com>

LEGO1/mxmediapresenter.h

@@ -15,14 +15,14 @@ public:
   virtual long Tickle() override; // vtable+0x8, override MxCore
 
   // OFFSET: LEGO1 0x1000c5c0
-  inline virtual const char *MxMediaPresenter::ClassName() const override // vtable+0xc
+  inline virtual const char *ClassName() const override // vtable+0xc
   {
     // 0x100f074c
     return "MxMediaPresenter";
   }
 
   // OFFSET: LEGO1 0x1000c5d0
-  inline virtual MxBool MxMediaPresenter::IsA(const char *name) const override // vtable+0x10
+  inline virtual MxBool IsA(const char *name) const override // vtable+0x10
   {
     return !strcmp(name, MxMediaPresenter::ClassName()) || MxPresenter::IsA(name);
   }