Replace text in a file doesn't update open tab

[mattpass]

The find and replace in files system works fine but if the tab is open it of course has got the old version of content.

If you try and save it will inform you the file has changed of course and show you the diffs so you can patch up as you'd like.

We should detect if the file is open in a tab first and ask the user if they wish to update in the open tab instead. OK will update in that tab and cancel will do nothing.