[s2804] Update M'uru script

* Implement Darkness and Singularity
* Fix encounter reset after [s2803]
* Allow DB to handle summons cleanup on reset

(based on commit SD2[3046] - e4133c7)

Signed-off-by: Xfurry <xfurry@scriptdev2.com>
[s2805] Fix faction of escortee Corporal Keeshan

Signed-off-by: Xfurry <xfurry@scriptdev2.com>

(based on commit SD2[3047] - 5d77c32)

Signed-off-by: Xfurry <xfurry@scriptdev2.com>