One can now mark a texture param in a material definition as linear by using -Linear at the end of the parameter declaration (case insensitive).
An Image bound to a material texture param in a linear color space will have its ColorSpace set to linear when bound to the material by mat.setTexture("name", texture);
Added the -LINEAR flag to all texture param that needed it in stock materials (lighting.j3md, terrainLighting.j3md, different Filter materials).
- All images constructors now take the isSrgb flag as a parameter, all engine classes has been changed to accommodate the change, old constructors has been deprecated for backward compatibility. One should always ask himself in which color space is an image if dealing with gamma correction
- Gamma correction has been defaulted to false in the appSettings
added a WindowListener in the constructor that overrides the windowsClosing method to dispose the TestChooser dialog.
code tested with positive result for issue#85.
