Blender Git Loki

GPUShader: Rewrite error printing

Now error printing only display the line related to the error.
We also put char marker if present.

Example:
```
-- Shader Compilation Errors : MAMaterial --

10414 | node_fresnel(, facingnormal, viewposition, tmp34);
| ^
| error: syntax error, unexpected ',', expecting ')'

----------------------------------
```