Far more careful LaTeX log parser
Far more careful LaTeX log parser

Upon closer inspection, it turned out the terminal output of TeX was
not as ambiguous as I thought.  This improves the precision of the log
parser for contexts and bad boxes and cleans up some other nits.

mhoogendoorn/latexrun,mhoogendoorn/latexrun,FranzSkuffka/latexrun,temporaer/latexrun,apuignav/latexrun,aclements/latexrun,msullivan/latexrun,FranzSkuffka/latexrun,aclements/latexrun,apuignav/latexrun,temporaer/latexrun,msullivan/latexrun