Dismiss hints when shift plus up arrow or down arrow is pressed
Changed Jump-To-Definition, as requested -- modeled on QuickEdit:

  - Now can register multiple jump-to-definition providers (only one, so far).
  - Moved jump-to-definition menu setup to top level.
  - Added jump-to-definition to floating right-click menu. [ Note: we may not want
    this unless there is a provider registered for the current mode, but that's how
    QuickEdit does it.  We can fix both at the same time if we decide to. Also note
    that if we want to change the right-click menu for this, one could argue that we
    should also change the top level menu for the same reason. ]
Commented out JUMPTO_DEFENITION from right-click context menu.
Fix code review issues:
 - Make handleJumpToDefinition return a proper promise.
 - Minor cleanups.
Merge branch 'master' of https://github.com/adobe/brackets into jumptodef

Conflicts:
	src/extensions/default/JavaScriptCodeHints/main.js
One more cleanup from the code review.
Merge pull request #4020 from jeffkenton/jumptodef

Changed Jump-To-Definition, as requested -- modeled on QuickEdit:
only record document changes for non-null keys
Merge pull request #4044 from dloverin/fix-ctrl-space

only record document changes for non-null keys
add PAGE_UP and PAGE_DOWN keys
Merge pull request #3955 from dloverin/shift-up-down

Dismiss hints when shift plus up arrow or down arrow is pressed
Tests for delete file/folder from project tree.
revert ctrl-space fix. Need to investigate possible problem with 'empty' updates.
Added close button to JSLint Panel.
Added JSLint Panel toggle.
Added JSLint Panel toggle.
Preventing disabled jslint icon from opening up the panel.
Stop JSLint Error from opening by pressing jslint-valid icon.
Remember lint panel collapsed state.
fix exception at startup