Y-Position of delimiters with \left and \right

[manuelbb-upb]

Vertical delimiter positioning is off with \left and \right.
These changes are factored out from #148 and should fix #110.
It is a back-of-the-napkin heuristic, but looks good:

Issue #110

text(0,-0.5; text=L"\left(\left|\left[\int\right]\right|\right)", fontsize=30, align=(:center, :center))

prototype.jl master:

prototype.jl new:

delimiter references master:

delimiter references new: