When pasting, retypeset math to get back context menu.

Also, use range machinery to insert pasted content. This is necessary because
InsertHtml breaks if any inserted content has no style property (math elements
doesn't), and insertIntoDOM pastes the content AFTER the selected paragraph,
when pasting content on a new line. This does the right thing by pasting it
inside the paragraph, or any other place your cursor might be.
Repair css so warning icon shows again.
Improve styling of warning icon
Improve styling of type/label switcher

- Bootstrappy style with span (or a).
- First dropdown text should now appear directly on top of the label
text.
- Made a few adjustments in the coffee files to fix bugs or to make
things consistent
arrow was too big in others' computers

Dunno why arrow character is really small in my machine/OS/browser. This
still looks small on my machine, but is "good enough", and looks much
better on Tom's and probably Kathi's.
prevent link popover from always wrapping

Decided to still let it wrap if close to the edge. That popover still
needs attention re: the icons, but it's better for now. The change to
the .coffee file was made to prevent extra spacing from getting
underlined, but I couldn't figure out a way to comment that section of
the file, so noting it here.
use actual label instead of literal "this element"

- "Advanced options for this [element]" instead of "advanced options."
- "Copy [element]" instead of "Copy element"
I also removed some periods because they bugged me, but if somebody
really wants them, I won't fight it.
No need to pass path to copy plugin buffer method anymore, it will now do this automatically.
Take a content-type option to buffer, similar to real clipboard.

This defaults to text/html.
Specify custom content type when duplicating copy to local buffer.
copy/paste handlers slightly modified to allow other code to trigger them.
Copy plugin delegates copy/paste via events

This allows the math plugin to handle pastes, even when the copy
plugin is doing it.
Merge branch 'copy-paste-math-v2' into testing

Conflicts:
	src/plugins/oer/assorted/css/image.css