RFC : field name identifier conventions

Following the earlier discussion I have created two patches which shorten the identifiers in some of the structs:

1) A patch for the CCIDs, where I used the scheme suggested by Arnaldo (i.e. "c<N>{tx,rx}", e.g. hcrx->c2tx_ssthresh). This resulted in a rather large patch (66k) and was rather disappointing - there was not much of the expected reduction in multiline expressions. For these reasons I think it is better to stick with the old scheme. But if people are still interested in this and may have different opinion, have a look at how the conversion looks at:

http://www.erg.abdn.ac.uk/users/gerrit/dccp/rfc_patch_new_ccid_field_ids.diff

2) A patch for ackvec.{c,h}. This follows next and simply replaces the `dccp' in the struct dccp_ackvec{,_record} fields. I like this patch because it makes the code easier to read.

Arnaldo can you please indicate whether you find this patch acceptable - I am working on Ack Vectors (adding a tail pointer and fixing acknowledging old Ack Vectors): if you are not ok with the patch, then I use the old scheme.