Autoreload Nagview (#942)

* Modified autoreload to use new dirwatch infrastructure, and added in nagview to verify that fs changes don't stomp on our changes, unless you want them to.

* Split out reload functionality to actual document, and added in a thread to check the document, in the cases where it wouldn't be covered by dirwatch.

* As per request from jgmdev, added in ability to show nagview always.

* Changed things over to use dirwatch.

* Made sure we redrew things, added in a contingency in 'save' for times when we load a non-existent file, and added some checks.

data/core/commands/doc.lua

@@ -466,6 +466,10 @@ local commands = {
       command.perform("doc:save-as")
     end
   end,
+  
+  ["doc:reload"] = function()
+    doc():reload()
+  end,
 
   ["file:rename"] = function()
     local old_filename = doc().filename