Fixed issue #21.
Added an additional tree filter to resolve issue #3 (Initialize
variables to their default value). Unfortunately, the knowledge about
the variable types is rather sparse, i.e., only seldomly a variable is
really initialized. This needs some improvement.
First implementation of use before init.
First implementation of read before write.
Beta version of the tree walker.
First working version of read before write resolver. No scope handling
yet!!!
Added declaration of loop variable in simple counting for-loops.
Added function-scope.