Vertical vectors have too much whitespace

[WhatisRT]

There are two separate issues here:

• The parentheses are in most cases a little further out than they need to be. Here's one example where it looks really odd:
• Sometimes extra horizontal whitespace is inserted even when in an AgdaSuppressSpace environment. Here's an example:

For the first case, I think it's best if we just make all the parentheses sit a little closer. For the second case, I assume there is some bug that generates an extra line somehow?