User request: lower gravity range minimum

[oliver-phet]

I thought I'd have my students vary gravity to match the planets/Moon/dwarf and was disappointed to find the setting doesn't go below 5 m/s^2
The moon is 1.62 m/s^2, Mars is 3.711 m/s^2, and Pluto is 0.62 m/s^2

[arouinfar]

The lower the gravity limit, the lower the terminal velocity can be. I think we ran into performance issues because there are lots of dots that need to be drawn on the path. I tried to find a paper trail for this, but I couldn't.

I'll test things locally with a lower gravity limit and see how it goes.

[zepumph]

@arouinfar, pinging you again on this since it is a high priority for our client again.

[zepumph]

From design meeting today with @arouinfar, @kathy-phet, and myself, we decided to try out a minimum of 1m/s^2.

Committed above.

This, in correlation to a variety of UI changes we will do to support a max initial speed of 100m/s over in #153, should cover the usability concerns and the feature.

[arouinfar]

Projectile Motion is an "if-time" quarterly goal, so marking as on-hold.

[matthew-blackman]

We are working on Projectile Motion as part of the data fluency grants, marking this off hold since we can address it as part of that work.

[arouinfar]

Unassigning myself until work on this flavor of Projectile Motion resumes.