Fix all blocks and samples on linux, add cairo support

[ppff]

I wanted to try Cinder for an upcoming project. I'm a full time linux user, and couldn't help but notice that most samples wouldn't build on Ubuntu 18.04.

Hence, I reviewed each block and each sample to make sure they now build and work (except those that aren't supported on linux of course). I added the samples that aren't supported to the CINDER_SKIP_SAMPLES list.
This also led me to add linux support for Cairo because I wanted to try the _svg samples. I've changed a few bits of code in the Cairo block, one should try to build it on windows and osx to make sure I didn't break anything. If you want a second PR just for that, I can rework my branch.

This PR should close #1483 close #2052 close #2022 and maybe close #1815 (most Cairo samples also require Renderer2D which is still not implemented on linux).

Any comments would be appreciated.

[richardeakin]

Really awesome that you took this on, thanks! It will be great to finally have all samples building in Linux, a big step in cross-platform equality. We're gearing up for a release within the very near future, so I think we'll try to get this work integrated within the next release cycle.

I think we should probably simplify this PR to things related to cairo / svg samples as much as possible. I haven't yet had time to review or run this code, but I hope that we can soon.

[ppff]

In order to make things clearer I created two separate branches from cinder/master and cherry picked my commits to them.
We should now work with the new PRs #2135 and #2136.