Fix pattern parsing

Signed-off-by: Christoph Höger <christoph.hoeger@tu-berlin.de>
Error propagation

Signed-off-by: Christoph Höger <christoph.hoeger@tu-berlin.de>
Merge branch 'master' of https://github.com/choeger/sl2

Signed-off-by: Christoph Höger <christoph.hoeger@tu-berlin.de>

Conflicts:
	src/main/scala/impl/CombinatorParser.scala
	src/main/scala/impl/ParboiledParser.scala