Feature: auto-detect map height limit based on generated map

This opens up the true power of the TGP terrain generator, as it
is no longer constrainted by an arbitrary low map height limit,
especially for extreme terrain types.

In other words: on a 1kx1k map with "Alpinist" terrain type, the
map is now really hilly with default settings.

People can still manually limit the map height if they so wish,
and after the terrain generation the limit is stored in the
savegame as if the user set it.

Cheats still allow you to change this value.

src/table/settings.ini

@@ -394,16 +394,16 @@ base     = GameSettings
 var      = construction.map_height_limit
 type     = SLE_UINT8
 from     = SLV_194
-guiflags = SGF_NEWGAME_ONLY | SGF_SCENEDIT_TOO
-def      = DEF_MAP_HEIGHT_LIMIT
+guiflags = SGF_NEWGAME_ONLY | SGF_SCENEDIT_TOO | SGF_0ISDISABLED
+def      = 0
 min      = MIN_MAP_HEIGHT_LIMIT
 max      = MAX_MAP_HEIGHT_LIMIT
 interval = 1
 str      = STR_CONFIG_SETTING_MAP_HEIGHT_LIMIT
 strhelp  = STR_CONFIG_SETTING_MAP_HEIGHT_LIMIT_HELPTEXT
-strval   = STR_JUST_INT
+strval   = STR_CONFIG_SETTING_MAP_HEIGHT_LIMIT_VALUE
 proc     = ChangeMaxHeightLevel
-cat      = SC_BASIC
+cat      = SC_ADVANCED
 
 [SDT_BOOL]
 base     = GameSettings