Revisions: Fix up some bugs I introduced while reviewing the mega revisions patch - when comparing two historical revisions only one half of the diff would load

See #23497 props adamsilverstein.
Revisions: Fix up some half renamed variables that break the view and display a mismash of split and combined views. See #23497 props adamsilverstein.
Ensure we strictly compare 'alloptions' and 'notoptions' when protecting these special options.

Trim and check for emptiness of $option in delete_option(), as done for get, update, and add.

fixes #23289.
In insert_blog(), make sure we retrieve the insertion ID from wpdb before calling a function that could invoke queries. props feedmeastraycat. fixes #23400.
Move admin bar initialization from init to template_redirect, so conditional tags may be used in the show_admin_bar filter. props scribu. fixes #20101.
Twenty Thirteen: style the multisite registration form, props kwight. Fixes #23631.
Twenty Thirteen: first pass at better color contrast for links. Also fixes very poor contrast for h3-h6 headings in footer widget area. Props jorbin and sabreuse. See #23513
Fix internal linking dialog conflicts with jQuery UI 1.10.x. Syncs jQuery UI CSS styles.

Remaining issue will be fixed in 1.10.2 final.
props ocean90.
see #23370.