Panel: Panel classes set on wrong page

Closes gh-6920
Fixes gh-6650
Updating the master version 1.4.3pre.
All: Fix demos markup inconsistencies discovered by cheerio

Closes gh-7212
Fixes gh-7211
Demos: highlight is now correctly removed on cancelation

In swipe to delete demo, the highlight is properly removed from the selected
list item on cancelation of the deletion.

Closes gh-6893
Fixes gh-6892
Demos: Pre-render collapsibles in demos left-side menu

Fixes gh-7225
Demos: fix style on listview-linkbar demo
Listview: linkbar demo scroll handler not working and updating to 1.4

Fixes gh-7129
Closes gh-7131
Page container: the load method now correctly returns a promise

The API docs for version 1.4.0 state that the load method of the pagecontainer
widget returns a promise. This commit adds this behaviour to the widget to
comply with the docs.

Closes gh-6901
Fixes gh-6900
Build: Use cheerio to update paths inside hrefs

Closes gh-7202
Fixes gh-6941
Fixes gh-6677
Checkboxradio: Retrieve form ID via .getAttribute()

Closes gh-7224
Fixes gh-7223
Selectmenu: Correctly pass theme and overlayTheme to popup

Closes gh-7196
Fixes gh-7195
Page: Attach unit test delegated handler to document instead

Closes gh-7235
Fixes gh-7234