Code for detailed tracing of LaTeX log parser

Trying to track down some problems parsing LuaTeX logs
Fix two problems related to LuaTeX wrapping logs at 80 columns

TeX, pdfTeX, and XeTeX all wrap their logs at 79 columns, but LuaTeX
currently wraps at 80 columns (LuaTeX bug #900).  This was breaking
some of the line-unwrapping code and causing it to misparse logs.  Fix
it by being more lenient and more careful during line unwrapping.