[Idea] New autobackup function

Regarding to this issue I had an idea:
https://github.com/arduino/Arduino/issues/3174

The ide has an autosave on compile function. This overwrites the file.
I am one of those guys who open old sketches, ruin them to try things out and close them without saving. So I do not want to enable this option for me.

A backup however would be nice if the IDE crashes again.
I'd go for a ~sketch.ino file like most editors under linux do. Then you always have a backup if the ide crashes, but its not saved directly. The backup can be saved in the directory itself or somewhere else. On exit it should clean those files. If it crashes, the next time it can ask if it should recreate those files or compare etc.

Start by examining the existing autosave-on-compile behavior referenced in the issue and how the IDE handles crashes and reopening sketches. The requested result is a crash-recovery backup that does not overwrite the sketch, is cleaned up on normal exit, and can be restored or compared after a crash.

Written by the indexing model from the issue text.