Update HACKING document to bring it up to date with latest coding.


git-svn-id: svn://vcs.exim.org/pcre/code/trunk@1390 2f5784b3-3f2a-0410-8824-cb99058d5e15
Minor documentation clarifications.


git-svn-id: svn://vcs.exim.org/pcre/code/trunk@1391 2f5784b3-3f2a-0410-8824-cb99058d5e15
Give errors for [A-\d] and [a-[:digit:]] etc.


git-svn-id: svn://vcs.exim.org/pcre/code/trunk@1392 2f5784b3-3f2a-0410-8824-cb99058d5e15