Eliminate unnecessary arrow crossing

[dwhatley19]

Arrows sometimes cross unnecessarily, as in this diagram:

Desired diagram looks like this (http://web.mit.edu/6.031/www/sp20/classes/10-abstract-data-types/#@now_same_client):

Snapdown:

s -> (MyString a -> #1, start -> 0, end -> 4)
t -> (MyString a -> #1, start -> 1, end -> 3)
#1 -> (char 0 -> 't', 1 -> 'r', 2 -> 'u', 3 -> 'e')

Arrows should cross minimally, only when necessary, or not at all.