Merge commit 'a8b575671894ffe1329ef37dca4989c0e60d70f5'

These merges are becoming more awful every time

Conflicts:
	src/ai/ai_gui.cpp
	src/build_vehicle_gui.cpp
	src/cheat_gui.cpp
	src/company_gui.cpp
	src/depot_gui.cpp
	src/dock_gui.cpp
	src/error_gui.cpp
	src/genworld_gui.cpp
	src/misc_gui.cpp
	src/network/network_content_gui.cpp
	src/network/network_gui.cpp
	src/newgrf_gui.cpp
	src/news_gui.cpp
	src/rail_gui.cpp
	src/rev.cpp.in
	src/road_gui.cpp
	src/settings_gui.cpp
	src/settings_gui.h
	src/signs_gui.cpp
	src/station_gui.cpp
	src/table/settings.ini
	src/terraform_gui.cpp
	src/toolbar_gui.cpp
	src/toolbar_gui.h
	src/vehicle_gui.cpp
	src/video/sdl_v.cpp
	src/viewport.cpp
	src/widget.cpp
	src/widgets/settings_widget.h

src/settings.cpp

@@ -1070,6 +1070,12 @@ static bool ZoomMinMaxChanged(int32 p1)
 	extern void ConstrainAllViewportsZoom();
 	ConstrainAllViewportsZoom();
 	GfxClearSpriteCache();
+	if (_settings_client.gui.zoom_min > _gui_zoom) {
+		/* Restrict GUI zoom if it is no longer available. */
+		_gui_zoom = _settings_client.gui.zoom_min;
+		UpdateCursorSize();
+		LoadStringWidthTable();
+	}
 	return true;
 }
 
@@ -1153,7 +1159,7 @@ static bool InvalidateCompanyWindow(int32 p1)
 static void ValidateSettings()
 {
 	/* Do not allow a custom sea level with the original land generator. */
-	if (_settings_newgame.game_creation.land_generator == 0 &&
+	if (_settings_newgame.game_creation.land_generator == LG_ORIGINAL &&
 			_settings_newgame.difficulty.quantity_sea_lakes == CUSTOM_SEA_LEVEL_NUMBER_DIFFICULTY) {
 		_settings_newgame.difficulty.quantity_sea_lakes = CUSTOM_SEA_LEVEL_MIN_PERCENTAGE;
 	}
@@ -1283,12 +1289,40 @@ static bool ChangeDynamicEngines(int32 p1)
 	return true;
 }
 
+static bool ChangeMaxHeightLevel(int32 p1)
+{
+	if (_game_mode == GM_NORMAL) return false;
+	if (_game_mode != GM_EDITOR) return true;
+
+	/* Check if at least one mountain on the map is higher than the new value.
+	 * If yes, disallow the change. */
+	for (TileIndex t = 0; t < MapSize(); t++) {
+		if ((int32)TileHeight(t) > p1) {
+			ShowErrorMessage(STR_CONFIG_SETTING_TOO_HIGH_MOUNTAIN, INVALID_STRING_ID, WL_ERROR);
+			/* Return old, unchanged value */
+			return false;
+		}
+	}
+
+	/* The smallmap uses an index from heightlevels to colours. Trigger rebuilding it. */
+	InvalidateWindowClassesData(WC_SMALLMAP, 2);
+
+	return true;
+}
+
 static bool StationCatchmentChanged(int32 p1)
 {
 	Station::RecomputeIndustriesNearForAll();
 	return true;
 }
 
+static bool MaxVehiclesChanged(int32 p1)
+{
+	InvalidateWindowClassesData(WC_BUILD_TOOLBAR);
+	MarkWholeScreenDirty();
+	return true;
+}
+
 
 #ifdef ENABLE_NETWORK