Big change: Introduced new mechanism to handle queries. It should not cause any visible changes ATM apart from fixing several long-standing bugs realted to handling post-visit/battle/levelup callback, including infamous  creature bank issues: #955, #1053, #1063, #1191. Needs testing.

Minor changes:
* default log level set to trace
* LOG_TRACE raii guardian lifetime will last till the end of block
* compile fixes
* minor refactorings

git-svn-id: https://vcmi.svn.sourceforge.net/svnroot/vcmi/trunk@3336 4dfc6b2a-8b31-0410-aa91-d6c70e3ac834