[book] big overhaul of chapter 4. Rewrite a lot of stuff for flow and clarity. Add an entire section about HLLCompiler and it's uses.
[book] big overhaul of chapter 4. Rewrite a lot of stuff for flow and clarity. Add an entire section about HLLCompiler and it's uses.

git-svn-id: 6e74a02f85675cec270f5d931b0f6998666294a3@38949 d31e2699-5ff4-0310-a27c-f18f2fbe73fe

ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot