This leads to more consistent formatting across entire Aiken programs.
Before that commit, only long expressions would be formatted on a
newline, causing non-consistent formatting and additional reading
barrier when looking at source code.
Programs also now take more vertical space, which is better for more
friendly diffing in version control systems (especially git).
Not sure what this special case was trying to achieve, but it's not right. There's no need to handle function call with a single argument differently than the others.
