sym class constructors accept column vectors

[bradley-solliday-skydio]

Previously, the class constructors would not accept column vectors. This is inconvenient because our generated functions accept column vectors and return column vectors.

So, this PR changes the constructors to accept column vectors as well (more or less, as row vectors and other funky shapes are also accepted).

Also, replaced assertions on user inputs with exceptions, and asserted that the user's input vectors, for example, aren't too long, as they were previously able to silently create wonky Poses (for example.

Notably, this commit does not change the from_storage methods to accept column vectors. This is because it's a bit less obvious that they should accept column vectors, and I wanted to save worrying about it for another day.

Fixes #246

[aaron-skydio]

I was sort of expecting these would have the same shape requirements as our generated functions as well? E.g. you can't pass something with more than 2 dims, and it has to be a vector as opposed to e.g. something 2x2?

[aaron-skydio]

We could even, for instance, try moving the dimension checking code into a jinja macro that we call from all these places and from expr_code? If that actually makes things nicer and isn't just a hassle

[bradley-solliday-skydio]

Alright. I'll check the sizes. And I'll consider the macro.

[bradley-solliday-skydio]

Can we also use flatten_if_ndarray for expr_code? Or is that more annoying

I thought about it and wanted to (because if I could that would cut down on code duplication and the like), but the checking we'd want to perform in expr_code is sufficiently different for there to not be a good way of doing it.

Specifically, there are a bunch of differences.

For the shape checking in expr_code:

• Our final shape is 2d
• We reshape only if the array is 1d
• We raise an IndexError if a row vector was passed in with a col vector was expected and vice-versa
• Need's to have an option to be made numba compatible

For the shape checking in the handwritten code:

• Our final shape is 1d (and needs to be something easily convertible to a list, if we don't convert to a list outright)
• We reshape only if the array is 2d
• We have no reason to discriminate between row vectors and col vectors
• Doesn't need an option to be made numba compatible

The result is that it wouldn't be pleasant to have one macro handle both cases.