implement a new parser

[mh-cbon]

implement a new parser based on https://github.com/mh-cbon/state-lexer
take chance of that change to add support for section
and more grained parsing capabilities.

Section would help to categorize messages.

0.9.12-1
  
  FIX
  * blah blah (Closes: #nnnn)
  * 0abcdef (typo) #15 Fix the typo in 'waht'
  * 0abcdef (break,closes) #12 Add config support to yInstance constructor. The new signature is `yInstance(c Config) yInstance`. blah blah.

  PREPARE
  * (minor) #18 improved performance for blah blah

  - mh-cbon <mh-cbon@users.noreply.github.com>

-- Josip Rodin <joy-mg@debian.org>; Mon, 22 Mar 2010 00:37:31 +0100

Parsing phase could be able to detect hash change, issue ticket number, status ticket, api compatibility change.
- [change hash] (close|fix|prepare,minor|break) #15 changed whatever in the project to make it better because i said so
Could the new parser support something to inject benchmark results into the changelog ? good idea ? benchcmp ?

% go test -bench=.
PASS
BenchmarkFib10   5000000               509 ns/op
ok      github.com/davecheney/fib       3.084s