STRAMBIO/NITSCHKE -- Increase number of slots for MultiLaserEngine from 6 to 8

[strambc]

Element name(s): LightSourceGroup/MultiLaserEngine

Justification for the addition (brief and compelling):
This suggested change came from a conversation with Roland Nitschke.
Roland mentioned that several MultiLaserEngines have 7 slots.
It was decided that 8 would be a good idea.

Full description of the proposed addition (enough detail to implement):
Modify the MultiLaserEngine icon as well as the Canvas slot for the MultiLaserEngine on the Canvas.

CANVAS CHANGE

Source of change (e.g., #XXX issue with change request): Roland Nitschke

THIS IS RELATED TO ISSUE #386

[strambc]

Planned for in release where Confocal Scanner will be released