new plain_fsm in jungerl

[Ulf Wiger (AL/EAB)]

I've checked in a new version of plain_fsm into jungerl.

The new features are mainly:
- a wider selection of start functions
- plain_fsm:hibernate(M,F,A), which does what
  erlang:hibernate(M,F,A) does, but also checks
  if the module has been upgraded, and automatically
  calls M:code_change/3 before resuming operation.

The parse-transformery has been completely re-written
and uses syntax_tools. I recently added some more 
controlled error handling, once I figured out how
to do that (it's not documented, but if you read
the code in compile.erl, the hooks are there.)

/Ulf W