Record line number on ParseError in valgrind

In __parseblocks(), catch any ParseError and record the current line
number on it.  Also record a TODO against the problems with how it
expects the file to be organised; can't cope with file-descriptor leak
reports.
Support uninitialized stack reads.

Also tidied MemoryChunk's setting of author and fixed a trivial error
in finalisation of all the parallel munchers in the parser.
Support one more variant on a cruft line in the footer.
Move attribute look-ups to initializers of arg-defaults.