Fixed: scratch views are not marked scratch in all ST events.

If a settings file is opened from within a .sublime-package, during the first few events it is not marked scratch by ST, so we have to check that it in fact exists on disk.
Doc tweak.
Temp files are kept in our own directory within the system tmp dir, so we can name the temp file the same as the original.
Some linters need LANG and LC_CTYPE set to utf-8 to work correctly with non-ASCII characters.
Fixed: checked the wrong name.
Factoring and cleanup.
Remove search for closest .sublime-project, it's too random to be useful.
Bump version.