Feature: add parallel projection

[mo-nonym]

Hello. Thanks for developing this interesting project! I was wondering about the possibilities to implement axonometric as well as oblique projection. I guess it’s a question about matrices. The first would be defined by a projection plane alone and the second by a projection plane plus an angle of the projection. Especially the oblique projection would be quite a uniqueness. It has its supporters and definitely a cultural relevance: Oblique Drawing.