Popup: Add ID to <h2> for popup position-to to find

Fixes gh-7875
Closes gh-7876
Demos: Complete page lifecycle description in introduction

Also, remove reference to deprecated data-rel="dialog"

Fixes gh-7833
Closes gh-7864
Toolbar: Only initialize this.pagecontainer if the toolbar is fixed

Fixes gh-7839
Closes gh-7860
Selectmenu: Close tag on wrapper
Slider: Close tag on wrapper

Re gh-6699
Fixes gh-7849
Closes gh-7859
Panel: Retain current page during closing process

Fixes gh-7814
Closes gh-7877
Panel: Make dismissible option work on-the-fly

Fixes gh-7882
Fixes gh-7884
Closes gh-7890
Panel: Test reaction to manipulation of dismissible option