Build: Upgrade to grunt-git-authors 2.0.0 and add update-authors task

Closes gh-1378
Tests: Adding missing dependency
Tests: Removing unused visual theme test
Theme: Change default widget font-size to 1em

Fixes #10131
Closes gh-1374
Menu: Wrap menu items in a <div>

This avoids styling issues where ui-state-focus rules apply to submenus.

Fixes #10162
Closes gh-1342
Autocomplete: Re-add wrappers to menu items
Selectmenu: Re-add wrappers to menu items
Theme: Carat should be named caret

Fixes #10683
Closes gh-1382
Selectmenu: Restore hidden overflow on menu items
Selectmenu: Introduce _renderButtonItem() method

Fixes #10142
Closes gh-1299
Sortable: Redetermine floating flag when recalculating positions

This addresses a bug where users initialize empty sortable lists are
add items dynamically. In this situation refresh() should recognize the
position and orientation of the new items.

Fixes #7498
Closes gh-1381
Selectmenu: Properly parse value from options

Fixes #10684
Selectmenu: Copy title attributes

Fixes #10435
Closes gh-1298
Tabs: Suppress automatic activation when navigating with COMMAND

Fixes #9621
Closes gh-1383
Droppable: Remove $.ui.intersect()

Fixes #10534
Demos: Fix menu markup in tooltip video-player demo
Demos: Fix menu markup in split button demo
Merge branch 'master' of https://github.com/jquery/jquery-ui into bug#9658
Changed resizable to support also DOMElements