Defining BP_ACTIVITY_SLUG breaks profile pages

[r-a-y]

As noted in the dev chat, defining BP_X_SLUG should still work in BP 1.3.

However, if we define BP_ACTIVITY_SLUG, profile pages break:
example.com/members/USERNAME/

When we define BP_ACTIVITY_SLUG, the current component should in theory still be 'activity', however this changes to whatever we define BP_ACTIVITY_SLUG to be.

One way around this problem is to:

• set $bp->default_component to bp_get_activity_slug() in the Members loader
• change bp_is_activity_component() to look for bp_get_activity_slug() as well

I'm not too fond of this approach, but this gets the job done without too much effort.

[boonebgorges]

Thanks, r-a-y. bp_is_current_component() is supposed to check against slugs as well as root_slugs, but something got messed up at some point (having to do, I think, with the move from $bp->active_components to the similar $bp->loaded_components). We'll set the default_component to the activity slugs (because in BP, current_component and its ilk come from the URL, ie the slugs), and then mod bp_is_current_component() to check slugs as well.

[boonebgorges]

(In [4882]) Ensures that bp_is_current_component() checks against slugs as well as rot_slugs. Sets members default component to activity slug rather than to 'activity'. Fixes #3398, props r-a-y

[r-a-y]

Thanks for clarifying about bp_is_current_component(), Boone. Makes sense!