Since the directory monitoring is now basically working we remove the
project scan thread periodically scanning the project directory.
Each project's directory is scanned only once at the beginning when
calling the function `core.add_project_directory` and is updated
incrementally when directory change events are treated.
The config variable `project_scan_rate` is removed as well as the
function `core.reschedule_project_scan`.
Francesco Abbate
rxi