print debug messages to stderr

Change-Id: Ic70e939cfe68a81165418482c2dc9e07473ef0b7
fix condition

Change-Id: I359a44e56ffecaa6d01b561a312cea9b3c1a4575
fix processing of mixed paragraph content

I would much prefer to do this in the parser, but calling closeSpan()
unconditionally just seems wrong and I do not want to introduce a new
function to ABWCollector just to be able to check if a span is opened.

Change-Id: Icf6950a5bbc8d401f5773270d23a45ddf2e41dcc
fix copypasta

Change-Id: I53bbd861af92e833f20333fc6db690b482bc313c