More coercion

[TodePond]

Many blocks can't be placed in other blocks, which isn't fun.

And types can't be used as other types, which isn't fun.

They should try their best to work!

[TodePond]

I'm not sure if ALL of these should be changed (!?), but here are some examples:

• [ ] Numbers should work as Vectors
• [ ] Vectors should work as Numbers
• [ ] Numbers should work as Elements
• [ ] Elements should work as Numbers
• [ ] Groups should contain anything
• [ ] Groups should work as anything

Identified gaps (incomplete list):

• [x] Set data should accept Group
• [ ] Set data should accept Vector
• [ ] Modify data should accept Group
• [ ] Modify data should accept Vector
• [ ] other gaps...