Change the default stand for the Manual microscope to the no_pi stand

The simple post stand is the most minimal stand, but is not optimal for stability of the Manual microscope. This MR makes the manual mounted on the microscope_stand_no_pi.stl by default.

Options to render the manual mounted on the simple post stand are kept, in order to give examples of the different stands available in the final build page.

Other sections that need to be modified:

• Printed parts list - replace simple post with no pi stand
• Prepare stand render view ports
• Prepare stand text (all four nuts/screws not just two)
• Mount the microscope - four screws not two
• Mount the condenser arm render view ports
• Attaching the sample clips render viewports

Optionally:

• Mention and render the microscope with the simple post stand

On hold until !311 (merged) is merged