Basically, to enable many nice features in Eclipse, like the ability to save a 
file and display cursor position markers in an editor, every IEditor will need 
a resource behind it, usually an IFile.

Right now, non-hosts get these StringEditorInput's or whatnot, which do not 
maintain a resource.  We need to change this so that non-hosts get temporary 
copies of shared files saved locally when they open them in an editor tab 
(prefix the filename with a . and it will not show up in their Project 
Explorer).

We should also probably delete the temp files on closing a shared file.  Or 
not, and allow the user to save them and keep a cache.