rules have a lot of repeated / reimplemented code

[oittaa]

There is quite a lot of repetition in rules like the same ID() function implementations everywhere. Additionally many functions just reimplement ContainsPkgCallExpr by manually looping over strings.

#1458 intends to fix this. Since I didn't want to break the interface I had to rename the ID variable to RuleID because it would have conflicted with the new default ID() function definition.

[ccojocar]

Fixed by #/1458