- did some preparations to ParseDrawTextureTags to allow using the same code for parsing tag lists generated by the VM.

- removed the fixed point alpha tag from DrawTexture and replaced all uses with the floating point version.

src/intermission/intermission.cpp

@@ -630,7 +630,7 @@ void DIntermissionScreenCast::Drawer ()
 			DTA_DestHeightF, pic->GetScaledHeightDouble() * castscale.Y,
 			DTA_DestWidthF, pic->GetScaledWidthDouble() * castscale.X,
 			DTA_RenderStyle, mDefaults->RenderStyle,
-			DTA_AlphaF, mDefaults->Alpha,
+			DTA_Alpha, mDefaults->Alpha,
 			DTA_Translation, casttranslation,
 			TAG_DONE);
 	}