Earlier one could never change a note type, and therefore its extension.
Now you can rename a note's filename to whatever and accordingly the
editor will change.
A warning message is shown when changing the file type.
Fixes#474
Certain Editors only support certain file formats. We can create an
editor either by -
* Giving it a Note, and letting it choose an editor based on the default
/ note metadata
* New Note with a file type
* New Note with a editor type + possible file type
