(svn r11399) -Feature(ette): transparency settings can now be saved and thus remembered.

-Codechange: Wrap all transparency settings in accessors, hiding the implementation
-Change: Clicking "transparent building" menu will toggle Houses And Trees only.  The other options can be used in the transparency gui.
Initial patch by Smatz (FS#1349), with some rework by BigBB and your humble servant.

src/water_cmd.cpp

@@ -30,6 +30,7 @@
 #include "newgrf.h"
 #include "newgrf_canal.h"
 #include "misc/autoptr.hpp"
+#include "transparency.h"
 
 /** Array for the shore sprites */
 static const SpriteID _water_shore_sprites[] = {
@@ -449,7 +450,7 @@ static void DrawWaterStuff(const TileInfo *ti, const WaterDrawTileStruct *wdts,
 			ti->x + wdts->delta_x, ti->y + wdts->delta_y,
 			wdts->width, wdts->height,
 			wdts->unk, ti->z + wdts->delta_z,
-			HASBIT(_transparent_opt, TO_BUILDINGS));
+			IsTransparencySet(TO_BUILDINGS));
 	}
 }