Fine mouse movement and handles will now only be active when actually
within a table, otherwise less frequent mouseovers are used to track if
in/out a table.
Hides handles when out of a table, preventing a range of issues with
stray handles floating about.

Formatting was not persisted on empty paragraphs, and was instead based
upon last format encountered in selection.
This was due to overly-hasty removal of other formatting code, which
this got caught it.
Restored required parts from prior codebase.

Also updated inline format button active indicator to reflect formats
using the above, so correct buttons are shown as active even when just
in an empty paragraph.

- Updating height/width setting to clear any inline CSS width/height
  rules which would override and prevent resizes showing. This was
  common when switching media from old editor.
  Added test to cover.
- Updated resizer to track node so that it is retained & displayed
  across node DOM changes, which was previously causing the
  resizer/focus to disappear.

- Updated toolbars to auto-refresh ui if it attempts to update targeting
  a DOM element which no longer exists.
- Removed MediaNode dom specific click handling which was causing
  selection issues, and did not seem to be needed now.

- Allowed re-editing of existing embed HTML code.
- Handled "src" form field when video is using child source tags.