scide: restore: delete all tmp files when discarding change

This patch makes sure there is no tmp files left when exiting SuperCollider and
discarding all changes.
scide: restore: add coalescing

This patch avoid to store tmp files at each document edition. It sets 100
modifications or 60 secondes of idleness before storing the restore tmp file.
scide: restore: use tmp folder into SC config dir

This patch lets restore feature to use its own folder into the SC config dir.