[nobug] markdownEditor.js: do not mutate marked's default options
[nobug] hover.js should sanitize HTML within Markdown
Bug 449008, bug 437849 - showWhile should not clobber existing status

* This was immediately hiding messages shown from a plugin calling the
  editorContext#setStatus(..) API
Bug 449860 - Problems view: Need to switch between two views based on the user's choice. -- generalized the common fileDetailRenderer shared between search explorer and problems view.
Bug 445234 - Incorrect link for _root folder page_ in Deploy notification