Improve authentication routine

[r-a-y]

In bp_core_signup_disable_inactive() and bp_core_boot_spammer(), checks are done against the $username parameter.

This isn't necessary; we should just use the passed $auth_obj and do checks against that as some plugins might already take advantage of the 'authenticate' filter and the $auth_obj variable (like the WP Email Login plugin).

(This ticket was created because of ​an issue with BuddyPress and the WP Email Login plugin.)

In the attached patch, I have renamed $auth_obj to $user, changed the authentication logic and cleaned up the PHPDoc for these two functions.

Let me know if you guys have any Qs!

[boonebgorges]

Good call, r-a-y - this looks right. I'm going to do some more testing in the next day or two, but it looks like it should be doable for this release.

[boonebgorges]

(In [6072]) Cleans up the authentication checks for spammers and inactive users

• Saves a lookup by examining the $auth_obj passed from the 'authenticate' hook instead of looking the user up by $username, in both bp_core_boot_spammer() and bp_core_signup_disable_inactive()
• Updates documentation for the relevant functions

Fixes #4245
Props r-a-y