[patch] layer context menus were different at two locations

[kolesar]

Right click menu on a map tile had "Snap to tile size" while popup menu in layer dialog had "Zoom to native resolution". The two actions did the same thing but was implemented twice.

There were items in both menus that had been missing from the another, combined them to be similar to each other in the same order. Some menu items had All Words Uppercased while others not, unified them.

Toggling [x] Show errors did not redraw map, it was confusing, fixed.

Item named "Change resolution" was also confusing and did nothing. This calls setZoomLevel(getBestZoom()) so that can be used as manual control when auto zoom is disabled. When auto zoom is enabled (that is enabled by default) it makes no sense. I have disabled this menu entry when auto zoom is enabled or current zoom is same as it would set to. Redraw was also missing, fixed.

The same issue was increase zoom and decrease zoom: did nothing with default configuration of tested version 9329 on standard mapnik layer, just because auto zoom was enabled. Disabled these when auto zoom is enabled and also when reached max/min levels. getMinZoomLvl() did not use the same way to obtain limit as getMaxZoomLvl() did, fixed.

Enabling "Auto zoom" did not change resolution immediately, only after moving map, fixed. Same for "Auto load tiles".

Added menu separators to emphasize which items belong together in a group. Now all corresponding items have the same names and order in two popup menus.

Attached patch.