SIMVoleon - Volumetric rendering library for Coin3D

This repo is forked from https://github.com/Alexpux/SIMVoleon which is (apparently) itself forked from the official one at https://bitbucket.org/Coin3D/simvoleon which I couldn't clone because of some hg config issues I was too lazy to solve...

SIMVoleon doesn't make use of cmake but rather of old-style configure & make system, which uses some old coin files that are no longer distributed in recent linux distros. So what I did here is add these needed coin files inside this repo, and modify the configure system so it finds them.

A note of warning, the coin-default.cfg included here was taken from the older libcoin80-dev package in debian, it works perfectly with libcoin80c currently in sid/buster. If you are using another distro, you might need to tweak some values inside.

So with this repo, to compile simvoleon successfully, you need to do these steps:

* Clone this repo
* cd <directory where you cloned this repo>
* /configure --prefix=/usr/local --with-coin=<directory where you cloned this repo>
* make
* make install (or use checkinstall)

Next I'll try to compile pivy with it...