[WIP] Export command

[o0Ignition0o]

Created an export command, which will allow to render a path and export it to a PNG or JPG File.
Still have to implement it though :).

This is one of the required steps to allow usage reftests later, as described in #193

[o0Ignition0o]

Tryouts to add a render method. It kind of displays fine, and I'm able to compute the window size, but I can't adjust the scene according to it. I'll figure it out later.

Once I found a way to handle this, I need to be able to render only one frame (maybe removing the while loop and executing it only once) and save the buffer to a BMP / PNG file.
Glad to see I'm moving forward though :')