c++03 -> c++11 switch:
- use std versions of function, bind and ref
- OVERRIDE -> override
- NULL -> nullptr
- use std versions of random distributions

NOTE: this may be last revision that supports gcc-4.5

git-svn-id: http://svn.code.sf.net/p/vcmi/code/trunk/@3429 4dfc6b2a-8b31-0410-aa91-d6c70e3ac834