LanguageMachines/libfolia: v2.4

comment in Doxygen format added bumped the library version to 14 fix for https://github.com/proycon/folia/issues/82 fix for https://github.com/proycon/folia/issues/42 fixed problem with using new tag names on pre 1.6 documents better checks in folia_engine on text inconsistencies and such (https://github.com/LanguageMachines/libfolia/issues/43) confidence output is more consistent now removed the folia_builder (was not used) code refactorings and cleanup, removing unused function