Password hashes are now stored in a TEXT attribute, not limited to 199 symbols.
That limitation makes no sense as password hashes are not the kind of
information to be indexed.
Actually replace crypt() with password_verify() for password checking, current
code left password_verify() unused.
Only update passwords when they use a different algorithm from the current
default. Previously "overwrite" meant rehashing every login.
Replace the "argon" boolean option with "algorithm" and "algorithm_options" for
better configurability.
The default remains whichever is default for PHP's password_hash.
For reference (raised by rozzin in IRC):
* http://foldoc.org/module
* http://foldoc.org/library
* http://foldoc.org/plugin
As noted by XRevan86, modules are not necessarily non-essential.
As we will keep the modules directory in GS root [therefore, near to
plugins/], it is evidenced the difference between both.
This is a simple yet fundamental structural change. It doesn't change
functionality but makes clearer the way we understand GNU social's
internals.
