Bug fixes & GetCapabilities, GetMap time-out ++

- Fixed an input hint and improved a user alert text-
- Fixed so that (again) the last-use text in ServerEditor updates upon
updating the layout, like after a successful connection.
- Fixed a bug that caused the layer mode "stored" to be possible to add
multiple times for the same layer, requiring the user to "delete" the
layer once for each "stored" mode added.
- Increased time-out time for GetCapabilities requests from 15 to 30
seconds. The response is ~150 kB and could take a while on slower
connections.
- Fixed a conncurrent editing error caused by removing records from a
collection while iterating. Now correctly uses the iterators remove
function.
- GetMap time-out also increased from 25 to 30s, see above.