- added A_Explode compatibility options.

There are two options here - one only disables the vertical thrust and the other goes back fully to the original non-z-aware code.
Both options are settable through MAPINFO.
For the compatibility presets, the normal ones only disable the vertical thrust, the strict ones force use of the old code entirely.

src/maploader/compatibility.cpp

@@ -165,6 +165,8 @@ static FCompatOption Options[] =
 	{ "teleport",				COMPATF2_TELEPORT, SLOT_COMPAT2 },
 	{ "disablepushwindowcheck",	COMPATF2_PUSHWINDOW, SLOT_COMPAT2 },
 	{ "checkswitchrange",		COMPATF2_CHECKSWITCHRANGE, SLOT_COMPAT2 },
+	{ "explode1",				COMPATF2_EXPLODE1, SLOT_COMPAT2 },
+	{ "explode2",				COMPATF2_EXPLODE2, SLOT_COMPAT2 },
 	{ NULL, 0, 0 }
 };