Fixed #178: Reset conditions if sameEntity is true

If a collector has an `sameEntity="true"` set, it is reset whenever
the current entity changes. As described in issue #178 the current
implementation fails to reset the condition during these reset
operations. This commit fixes this.

Additionally, the test cases for the if-condition have been moved
into a separate xml-file as quite a number of tests have
accumulated so that it makes sense to keep them in there on test
file.