debugging toStrings
Clear stack before reuse (not total fix)

This stops methods ending up as part of other people's stack traces, but
doesn't stop them from getting entirely lost.

This fixes the "Thread.run" bug, where lots of leaves would be followed
by Thread.run, instead of just ending as they should.
Merge pull request #47 from FauxFaux/master

LogParser clears the stack before reuse (not total fix)