Move bp_core_load_admin_bar() to bp_init, and also move the function itself into bp-core-adminbar.php next to bp_core_load_admin_bar_css(). Fixes bug causing current user to be loaded out of order. Fixes #4803. See #3661.
Only link 'Groups administration panel' on Welcome screen if Groups is active

See #4800

Props imath
POT, generated from r6763
Add _doing_it_wrong() feedback to bp_setup_current_user(), to help debug role and capability issues when the current user is prematurely loaded.
POT, generated from r6765
Add textdomain to  _doing_it_wrong() feedback in bp_setup_current_user().
On new install screen, don't link Members and Activity directories if pretty permalinks aren't enabled

Fixes #4800
POT, generated from r6768
Improvements to automatic WP page mapping for BP directory components

Since the wizard was removed, and Members and Activity were set as the default
components, BP has been creating directory pages for Members and Activity
automatically upon installation. This created a jarring disparity for the
Groups component, which also needs a top-level directory; when activated at a
later date, the user would be prompted to associate a page manually.

This changeset moves bp_updater_add_page_mappings() to the core component
(renaming it appropriately). This function is refactored to allow for existing
page mappings to be retained, as you'd want to do when activating new
components (rather than deleting existing mappings and mapped pages, as you'd
want during a fresh installation). Finally, the function is called when saving
the Components admin page, so that components requiring directory pages (like
Groups) get them created automatically upon activation.

Fixes #4805
Pinking shears
POT, generated from r6771
Use link to BP Codex Theme Compat page on bp-about.

Fixes #4807

Props modemlooper
POT, generated from r6773
Remove unneeded prepare() call in bp-xprofile-classes.php. Fixes #4654.
POT, generated from r6775
Update group admin logic to not allow moderators to save group settings via POST. Fixes #4737, props mercime
Update bp_forums_reply_exists() to use external helper filter instead of escaped create_function() usage. Fixes #4758.
Variable cleanup to bp-forums-functions.php.