Variable interfacing

[aconstlink]

A major problem is how to properly and generically interface with variables in order to connect engine layers.

For UI purposes, the property system exists. For real-time the wire framework is used. But how can the engine interface with random variables in order to expose them as properties or as slots in a wire node.

So I try to implement a variable interfacing library that exposes more information about variables but still have them efficient enough to be used during run-time.

This can be used to connect to keyframe animations, other computations or a UI property sheet in a generic way.

[aconstlink]

I actually experimented with meta data and some stored setter/getter stuff. But it turned out that is sucked, so I changed my mind and moved everything to wire.

In wire, there will be a variable type which will exactly do what we need.

I.e. connecting to variables/subvariables through slots. So there will be no unsafe pointer bingbang. It then will also nicely integrate into the concurrent node framework.

[aconstlink]

Introduced a wire variable bridge which exposes shader variables to the slot system. I did this because I decided to use slots in the scene graph instead of the wire variables because those mutated a bit...

[aconstlink]

New problems emerged when using input slots in with the new wire_variable_bridge in graphics. We need to determine the exact type between textures, arrays and streamout buffers or any other type to come. The change is already done but needs to be checked in.