Get/GetKey/SetKey/DeleteKey methods are used for access to
email/discord/telegram/matrix, everywhere. Mutex added for each, avoids
concurrent read/write issues. Will also make potential transition to
database easier.
names with no discriminator are shown as @username, and search works
with the @ too. Also bumped go version to 1.20, since it was stuck on
1.16 and i felt like trying generics (in an ugly way).
"Require unique ..." Settings (`require_unique` in relevant sections of
config.ini) are now available for email/discord/telegram/matrix. An
error is shown on the invite form if a non-unique address/ID is used.
This was on my kanban without a link to an issue, so i'm guessing it was
requested on Discord.
Harvey Tindall