Add "New" and "New Window" File commands

[GoogleCodeExporter]

"New" file command will create a new request (like Clear button, but prompts 
you to Save current request if it is dirty)

"New from Template..." or just "New..." is like the "New" command, except it 
lets you choose a template request for the new request (vs. opening a template 
file + Save As..., which risks overwriting the template).

Original issue reported on code.google.com by [email protected] on 5 Mar 2013 at 4:33