Since 1.0.1:
- Use OClosures to represent PEG rules when available, and let cl-print
  display their source code.
- New PEX form (with RULES PEX...).
- Named rulesets.
- You can pass arguments to rules.
- New `funcall' rule to call rules indirectly (e.g. a peg you received
  as argument).

Version 1.0:
- New official entry points `peg` and `peg-run`.