llvm 2.4 release notes draft

Hi All,

I am done with my first pass over the release notes, you can see them in mainline here:

In addition to the inevitable typos and other things that need to be cleaned up, there are several todo's for specific people:

1. All: please let me know if there is something missing that I forgot.
2. Daniel, please update the clang section [DANIEL].
3. Ted, please update the 'smoosh' section [TED].
4. Nicholas, please update the vmkit section [NICOLAS].
5. Bruno, please add a description of your changes to the Mips backend [BRUNO].
6. Dan, please describe your recycler changes if you want or remove the bullet [DAN].
7. Devang, please describe the API changes for your attributes stuff [DEVANG].

I'd strongly prefer you guys to just check in your changes, no need to email me. Just commit to llvm/docs/ReleaseNotes.html.