Idea: relative right, left, top, bottom based on styler symbol

I think it would be neat to do something like this in a stylesheet

``` ruby
def thing1(st)
st.frame = {
t: 5,
l: 5,
w: 10,
h: 10
}
end

def thing2(st)
st.frame = {
below: :thing1,
right_of: :thing1
w: 10,
h: 10
}
end
```

and it would put `thing2` at: `[15, 15]`

We'd have to think of how we might be able to integrate spacing in this so like I want to place something to the right of element `thing_n` plus 10 points, for example.

Thoughts?

No files, tests, or entry points are named. Start by locating stylesheet styler symbol handling and frame assignment, then determine how below/right_of references and spacing should work. Done means relative positioning is implemented with a clear syntax and verified behavior for the shown example.

Written by the indexing model from the issue text.