I have done a very initial patch in an attempt to define where we should
go with this feature. There are several different proposals around this
issue and the superseded one, I opted to implement the simplest one
which is to add a 'Revert' entry in the file menu which re-reads the
file currently open.

There are at least two problems with this patch. First, I don't think
there is a non-hacky way to place a command on a menu in a specific
place by using an idle extension, so, the 'Revert' entry is the last
entry in the file menu right now. I guess this would be solved by not
making this an extension and then proceed to manually remove the menu
entry while creating the shell window (similarly to what it is done when
running under mac osx). The second problem happens when reverting the
file, I'm not sure if it should be done differently but this seems to
cause some problem with Multicall.