Limit GUI scale by window size, fix tooltip dash glyph

Manual GUI scale is now limited so that UI is never smaller than
640x480 units (as in other games), otherwise menus did not fit the
window at scale 3-4 in small windows. The unsupported en dash in the
setting tooltip is replaced with a hyphen.

src/settings.hpp

@@ -41,7 +41,7 @@ struct DisplaySettings {
     FlagSetting limitFpsIconified {false};
     /// @brief Adaptive framerate in menu (experimental)
     FlagSetting adaptiveFpsInMenu {false};
-    /// @brief GUI scale factor (0 - auto, 1..4 - fixed integer scale)
+    /// @brief GUI scale factor (0 - auto, 1..4 - integer scale limited by window size)
     IntegerSetting guiScale {0, 0, 4};
 };