conf: support AccountStorage as well as Account_Storage
These variables added way back in b73ac9c3 ("Add support for 'primary'
and 'migrate' account storages. [...]", 2005-12-14). I think that
these have never been used by anyone, I think Dennis's out-of-tree
MySQL backend is the only storage backend anyone bothered to write.
That backend uses "AccountStorage" in the config, not
"Account_Storage". Let's support that, we could just change this over,
but *maybe* someone uses it out of tree, and supporting their config
in that case is easy.
I'm forward-porting https://github.com/bitlbee/bitlbee/pull/67 there's
production code that uses the CamelCase variant, and it would be handy
if it worked as-is without needing to fiddle with the config.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@…>
