Use keypress event

[bantic]

Use keypress event to accept character input

Previously, character input was detected after-the-fact using the mutation observer.

Other changes:

• Add Logger class with enable/disable/enableTypes methods.
  Used to selectively turn on/off logging for different parts of the editor.
  Disabled by default
• Add EditState class that is responsible for determining the current
  state of the editor (active markups, active sections, whether the next
  character will have any markup applied to it)
• Refactor the timing of cursorDidChange callback events --
  • Do not fire cursorDidChange before the editor has rendered
  • Eagerly fire cursorDidChange when active markups or sections
    (but not necessarily the cursor) has changed. This provides compatibility
    for consumers that rely only on the cursorDidChange method to update the
    state of their toolbar buttons, e.g.
• Change usage/lifecycle of editor.range -- now editor.range is cached until
  an event that may change the cursor (keystrokes, clicks, etc) occurs. This makes
  editor.range more stable and more performant. This obviates some complicated
  Adds _resetRange private method to force re-reading the range from DOM.
  editor.range is lazy — it only reads from the DOM when it is accessed.
• Refactor PostEditor slightly to read and render editor's range in light of
  the changes to editor.range
• Removes all usage of document.execCommand
• Enables most tests that were turned off for IE. Only copy-paste tests are skipped
  in IE.
• Adds test helper skipInIE
• Adds insertText method to editor that inserts text at the current cursor position
  with the markups from that position (if the cursor is in bold text, more bold text will
  be inserted).
• Adds EventManager class, moves event handling from Editor to EventManager
• Adds insertText and insertTextWithMarkup to PostEditor
• Change Post#markupsInRange to determine the markups correctly if the range is collapsed
• Change Key to correctly determine if an event is a key event or is in printable in Firefox
  because Firefox reports event.keyCode as 0 for some key events.

[bantic]

released in v0.9.0