AH (Ad Hoc) waveform format read support

AH v1 should be fine.
AH v2 tests need some real examples + ASCII equivalents to finish this PR - unfortunatly I couldn't find anything useable :/

Anyone got some AH v2 files? @jsaul, @jwassermann?
its tested with the files which came with the AH package - however I don't have any real example - I would leave it as it is and wait for the first error report