update manual Introduction and Foreign types, texinfo idioms throughout
update manual Introduction and Foreign types, texinfo idioms throughout

- Remove note on cffi-luis branch.
- Write introductory chapter.
- Acronym/sc-ify CL implementation names.
- Use @cffi{} instead of CFFI.
- Use @impnote for notes from luis and james.
- Split existing type translator explanation to make "Defining
  typedefs" and rewrite the former.
- Invent an example for defcstruct, and explain its limitations.
- Write "Allocating Foreign Objects".
- Move with-foreign-object(s) to Pointers chapter, to group it with
  foreign-alloc.
- Use @sc and @result to make REPL examples pretty, and move them into
  @example sections.
- Remove commented-out sections; they can be readded later from darcs
  repo if need be.

marsijanin/cffi,dkochmanski/cffi,attila-lendvai/cffi,wesen/cffi,3b/cffi,marsijanin/cffi,dochang/cffi,kingcheez/cffi-cheez,kingcheez/cffi-cheez,wesen/cffi,akovalenko/cffi,3b/cffi,stassats/cffi,attila-lendvai/cffi,mcna/cffi,wesen/cffi,mcna/cffi,dochang/cffi,dkochmanski/cffi,stassats/cffi,dkochmanski/cffi,akovalenko/cffi,cffi/cffi,3b/cffi,cffi/cffi,stassats/cffi,dochang/cffi,akovalenko/cffi,marsijanin/cffi,cffi/cffi,kingcheez/cffi-cheez