File Monitoring 2.0

[adamk]

While I have it in my head, here is my proposal for an upgraded file monitoring mechanism.

Monitoring will continue to occur as per normal for the currently active document, at periodic intervals, with a popup/warning to notify the user of any changes.

Monitoring will not occur for documents that are not in focus (or when Padre is in the background).

The out-of-date/deleted check will occur only when the document assumes focus. i.e. When the user switches the focus to that document. Even so, it will still occur in the background, and a slight delay between switching to a file and the warning dialog is acceptable (as long as this time is near or below the perceptual threshhold of the changed editor).