Create entry for 1.5 in the change log.

Starting it of with some of the changes that have been made to quickbook
since 1.4 - considering the first 1.4 release as the proper 1.4 release.

svn path=/branches/quickbook-1.5/doc/; revision=53448
Implement static/lexical scoping for 1.5. Refs #2034.

svn path=/branches/quickbook-1.5/doc/; revision=53451
Teletype source mode. Refs #1202.

svn path=/branches/quickbook-1.5/doc/; revision=53454
Ignore spaces after 'section:' for quickbook 1.5+ Refs #2712

And warn when section id is empty after colon.

svn path=/branches/quickbook-1.5/doc/; revision=53734
Remove old quickbook branch.

svn path=/branches/quickbook-1.5/doc/; revision=68344