Miscellaneous fixes:
- proper block of "back" button in campaign menu.
- proper block of AI switch in battles
- vertical garrisons can now be attacked from top
- better UI logging, vcmi will print to log file all pressed buttons
- server will not try to build already existing building


git-svn-id: http://svn.code.sf.net/p/vcmi/code/trunk/@3709 4dfc6b2a-8b31-0410-aa91-d6c70e3ac834