web: Remove links to missing binary packages
Since 2.21.0, we've dropped the following architectures:
- freebsd-x86, freebsd-64
I argue that they're equally meaningless for the current stable release (2.20.0), so drop as well. If a user wants to download the packages, they can be found at http://lilypond.org/downloads/.
While at it, clean up the version headers:
- Download always refers to the current stable version.
- Development always links to the current unstable binaries, but the manuals of the current commit.
This needs some love from the translators for the headers and warnings in the respective download.itexi.
I initially meant to get rid of
weblinks.itexi entirely, but the majority in there are translated links to all of LilyPond's manuals. This needs some more thought than I can currently give that.