Using the built-in FSMonitor makes many common commands quite a bit
faster. So let's teach the `scalar register` command to enable the
built-in FSMonitor and kick-start the fsmonitor--daemon process (for
convenience).
For simplicity, we only support the built-in FSMonitor (and no external
file system monitor such as e.g. Watchman).
Helped-by: Junio C Hamano <gitster@pobox.com> Helped-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Matthew John Cheetham <mjcheetham@outlook.com> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Victoria Dye <vdye@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>