Bug fixes for and improvements to changes2html.pl, which generates Changes.html from CHANGES.txt:
- When the current location has a fragment identifier, expand parent sections, so that the linked-to section is visible.
- Properly handle beginning-of-release comments that don't fall under a section heading (previously: some content in release "1.9 final" was invisible).
- Auto-linkify SOLR-XXX and INFRA-XXX JIRA issues (previously: only LUCENE-XXX issues).
- Auto-linkify Bugzilla bugs prefaced with "Issue" (previously: only "Bug" and "Patch").
- Auto-linkify Bugzilla bugs in the form "bugs XXXXX and YYYYY".
- Auto-linkify issues that follow attributions.