slider: converted the example from xhtml to html

(cherry picked from commit d5433185c89a44c4b5c3c5dcf579ced781f25c09)

Conflicts:
	entries/slider.xml
popup.xml: various formatting fixes

(cherry picked from commit 8c8c3c6aee757208b663cc807bc9cfe27bb0ce7e)

Conflicts:
	entries/popup.xml
panel.xml: various formatting fixes

(cherry picked from commit 4188f5954fe485fde07b777c971babceda06fff1)

Conflicts:
	entries/panel.xml
navbar.xml: replaced spaces by tabs in the final example

(cherry picked from commit 4ff2f65171f6b4e66d71b5086af55afe7cdc4315)

Conflicts:
	entries/navbar.xml
collapsible.xml: added missing spaces after ':'

(cherry picked from commit 8d63a86988d3b6251f080f647075bc4359ae4d17)

Conflicts:
	entries/collapsible.xml
checkboxradio.xml: moved the code examples to be html rather than xhtml

(cherry picked from commit 895b6aa744525178c19fe58193975954c0f4fd1f)

Conflicts:
	entries/checkboxradio.xml
buttons.xml: moved the code examples to be html rather than xhtml

(cherry picked from commit 1f4bebf3a887a556e11174fc3e68a3d911c42cac)

Conflicts:
	entries/button.xml
textinput: themeable spelling changed to be inline with all the other pages/sites

(cherry picked from commit 2d67dae32aeb0c426c8f3692322bf3663ee1c4b8)

Conflicts:
	entries/textinput.xml
api mobile docs: code formatting according to the jQuery guidelines

(cherry picked from commit b5d71f8675ae5fcd55d5eb34f64d7f8f40908a69)
Includes: Adding core-extension-desc.xml