* Drop "-rc1" from version in Makefile
* Sync (bump date) in docs & manpage
* Bump date in CHANGES.txt
* Bump date in appdata file (`org.tuxpaint.Tuxpaint.appdata.xml.in`)
* Bump copyright year in `win32/resources.rc`
Make headers and description terms more apparent, by adding
some more regexps into the `sed` that the HTML is piped through
before being sent to `w3m`.