update license link to LGPL 3
(cherry picked from commit 04fee37767d9ceec33870a304dbc4bbabf6f38ee)
create download page for (version, distro) only when installers exist

Previously, created every page in (all-versions X all-distros).
(cherry picked from commit 202dc90d96fceae4c998f0452188e753fe1b9d55)
handle new installer info lines
(cherry picked from commit 9aeadbe65e9a83aa54135e63bac762422833ff34)
change all versions download page to accommodate racket-minimal distro

Change from fixed 2 options (Racket, Textual) to flexible
(Racket, alternatives).
(cherry picked from commit caed4a04442eb4090ca2bab01a268174d262bd58)
add link to planet from community page
(cherry picked from commit 4c7a3b91ee72978a34427cd0fba969761c9bc527)
add symlink to releases dir
(cherry picked from commit ae6fc3f47f971975bc96b1e334ecaec026a95e95)
Update version number for the v5.92 release