Standalone HTTP header parser!

I've finally broken out enough of the HTTP header parsing code from src/ into libhttp/ to run the http header parser standalone.

This allows me to write some test cases to make sure I don't break things whilst changing how the HTTP header parser and HTTP header entry code uses (ie, abuses!) the memory allocator. It's also one step closer to being able to reuse bits of the Squid internals in a "simpler" HTTP proxy core.

I'll commit this code reorganisation to Cacheboy trunk after I've released and tested a few developer previews.

So, without further delay:

test1b: test parsing sample headers
| init-ing hdr: 0x7fffffffe6f0 owner: 2
| parsing hdr: (0x7fffffffe6f0)
Host: www.creative.net.au
Content-type: text/html
Foo: bar


| creating entry 0x60ed40: near 'Host: www.creative.net.au'
| created entry 0x60ed40: 'Host: www.creative.net.au'
| 0x7fffffffe6f0 adding entry: 27 at 0
| creating entry 0x60eda0: near 'Content-type: text/html'
| created entry 0x60eda0: 'Content-Type: text/html'
| 0x7fffffffe6f0 adding entry: 18 at 1
| creating entry 0x60ee00: near 'Foo: bar'
| created entry 0x60ee00: 'Foo: bar'
| 0x7fffffffe6f0 adding entry: 68 at 2
  retval from parse: 1
  Parsed Header: Host: www.creative.net.au
  Parsed Header: Content-Type: text/html
  Parsed Header: Foo: bar
| cleaning hdr: 0x7fffffffe6f0 owner: 2
| destroying entry 0x60ed40: 'Host: www.creative.net.au'
| destroying entry 0x60eda0: 'Content-Type: text/html'
| destroying entry 0x60ee00: 'Foo: bar'