- Various improvements for exploration
* Heroes will try to use SectorMap if there are no accessible tiles
* Remove some loopholes and pitfalls when all the ways are blocked
* Fixed AI not conquering some (reserved) objects
Still missing: SectorMap does not use Subterranean Gates :(

- Improvements for army exchange
* Fixed exchange condition
* Bidirectional exchange is possible

git-svn-id: http://svn.code.sf.net/p/vcmi/code/trunk/@3756 4dfc6b2a-8b31-0410-aa91-d6c70e3ac834