Removing an element of a MultiArray doesn't actually remove it from being published

[felixduvallet]

(I found this to be unexpected behavior when testing your fix for #17 , but this could just be a Garbage In -> Garbage Out problem. Feel free to close as wontfix.)

When publishing a MultiArray topic, removing an element in the GUI doesn't actually remove it from being published on the topic.

For example,

• Publish a MultiArrayFoo with one element -> len(data) = 1
• Add an additional element -> len(data) = 2
• Remove element data[1] -> len(data) = 2 still (I would have expected 1), and the last stored value gets published in data[1].

On a related note, removing an element that is not the last (e.g., data[1] with 3 elements) also keeps publishing the last stored value in data[1]. Perhaps setting the value to zero could be more intuitive.