Add an option to assume that the editor is the only source of changes to files?

[TysonAndre]

E.g. don't traverse configured files in directory_list such as vendor/, etc, checking for changes to modification date or file size every time there is a change that needs to be analyzed.

Skipping this should bring down latency somewhat, especially without SSDs

• Maybe re-check at most once per 60 seconds instead of every time.

This requires changes to the backend (only for language server, not for phan's earlier Daemon classes)

didOpen/didChange/didClose/rename/etc should be sufficient for most uses.

This may require refactoring the server to be able to check a single file against a list of inclusions and exclusions.

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Switching between git branches would break this assumption.
Maybe didChangeWatchedFiles might help?