- "lambda" statement logic changed, now there are three different
  ways to invoke a lambda. "lambda.copy", "lambda.immutable" and "lambda",
  which do roughly what they intuitively sound like they're doing
- changed all lambda keywords to drop the "pf." parts for simplicity
- change "for-each" to now internally use "lambda" for simplicity and
  clarity
- execution engine is now roughly finished in regards to its API - I think ...
- slightly improved the way "pf.console.write" (-line) functions. still
  needs more improvement, but getting there ...