sundry changes: grammar, out-of-date, typo, spaces, ...

- Add the () special case literal.
- private method calls only resolve to current class by default
- mention need for & in <&some_regex>
- explicitly type out bit shift operators
- file tests are no longer Pair.Bool
- lazy lists can be slower due to switching overhead
- lazy scalars are NYI
- completely removed section on postcircumfix methods and
  circumfix macros.
- use :exists instead of .exists for hashes
- self-declared parameters and signatures are mutually exclusive
- can't give an enum a type (like "bit").

I ran out of steam before doing chapter 17.