(svn r26289) -Codechange: Make tile areas and iterators more consistent to each other.
(svn r26290) -Codechange: Use nicer orthogonal tile iterator constructor and simplify calculation of explosion points when clearing.
(svn r26291) -Fix [FS#5866, FS#5888]: Correctly identify opposite ends of bridges and tunnels when converting rails (adf88)