Acceleration.BaseDimensions.IsBaseQuantity() returns true

[lipchev]

Describe the bug
The BaseDimensions.IsBaseQuantity() function filters out all dimensions that are <> 1, before taking the count- which is incorrect for something like the Acceleration with it's dimensions of [1, 0, -2, 0, 0, 0, 0].

To Reproduce
Acceleration.BaseDimensions.IsBaseQuantity()

[angularsen]

I believe this is a duplicate of #1430

[lipchev]

@angularsen Note that only the "Fix a bug in BaseDimensions.ToString() (#1431)" has been carried over into v6, the IsBaseQuantity was not. I'm going to create another PR for v6 - I think my version of the fix is slightly better.

[lipchev]

Oh, i see- this was only fixed 4 days ago- I thought that both issues were from months ago..