Move main executable source to its own directory (#248)

* Move main executable files to their own directory

* Adapt the build to the new file structure

... and fix some weird #include's that were relying on the project root
being an include directory.

Ja2/gamescreen.h

@@ -0,0 +1,44 @@
+#ifndef _GAMESCREEN_H
+#define _GAMESCREEN_H
+
+
+#include "fade screen.h"
+
+#define		ARE_IN_FADE_IN( )		( gfFadeIn || gfFadeInitialized )
+
+
+
+void FadeInGameScreen( );
+void FadeOutGameScreen( );
+
+typedef void (*MODAL_HOOK)( void );	
+
+
+extern BOOLEAN	gfGameScreenLocateToSoldier;
+extern BOOLEAN	gfEnteringMapScreen;
+extern UINT8		gubPreferredInitialSelectedGuy;
+
+
+void EnterMapScreen( );
+
+void UpdateTeamPanelAssignments( );
+
+
+
+
+
+#define TACTICAL_MODAL_NOMOUSE			1
+#define TACTICAL_MODAL_WITHMOUSE		2
+
+extern MODAL_HOOK		gModalDoneCallback;
+
+void EnterModalTactical( INT8 bMode );
+void EndModalTactical( );
+
+
+// handle the entrance of the mercs at the beginning of the game 
+void InitHelicopterEntranceByMercs( void );
+
+void InternalLeaveTacticalScreen( UINT32 uiNewScreen );
+
+#endif