Revert "Made the indirect prefer avoid actually traverse the tree"

This reverts commit 94dc68364bd7c418a4c11cb98367cd72f850ad39.
Fixed CountPreferAvoid in case of preferred trees

Using the correct collection to iterate over after already throwing away trees.
Fixed DrAmbiguity

Added other kind of productions to the alt2rascal function to pretty print productions.

a associativity is printed as Symbol = left production a priority as Symbol > production

@jurgenvinju or was this actually a bug in DrAmbiguity?