New shader keywords

Hello all,

here is a list of all the new shader stage keywords and what they are for.

// a single value representing the specular level
// non metallic surface values range between 0.04 and 0.08
// which translates to 4% to 8% reflectance
// metallic surfaces have higher reflectance
// this value is in linear space in range [0.0, 1.0]
specularReflectance <value>

// sets the stages gloss value in range [0.0, 1.0]
// 1.0 beeing a perfect mirror and  0.0 beeing a very very dull rock
gloss <value>

// the same as gloss, but reversed, pick what you like better
// roughness = 1.0 - gloss
// value is also in range [0.0, 1.0]
roughness <value>
  
// controlls the depth of the parallax correction when a
// normalHeightMap is supplied to the stage
// value is also in range [0.0, 1.0]
parallaxDepth <value>

// shifts your parallax correction out of the surface
// helps with floor materials creating gaps between floor and walls
// value is in range [0.0, 1.0]
// can be forced on all surfaces for testing purposes
// with r_forceParallaxBias when cheats are enabled
parallaxBias <value>

// scales the values of the supplied normalMap
// can flip normalmaps green channel so you can use opengl format normal maps too
// eg. normalScale 1.0 -1.0
// height value overwrites parallaxDepth when normalScale is written after parallaxDepth
normalScale <xy>
or normalScale <x> <y>
or normalScale <x> <y> <height>

// r, g and b values are specularReflectance of the surface
// gloss is gloss obviously
// overwrites specularReflectance, gloss or roughness if written after those keywords
specularScale <rgb> <gloss>
or specularScale <r> <g> <b>
or specularScale <r> <g> <b> <gloss>
  
// sets a stages normal map or a normal map with a height map in the alpha channel
// for parallax mapping
normalMap <name> 
or normalHeightMap <name>

// sets a stages specular gloss map
// must have a gloss map in the alpha channel, else the material will always be mirror like
specMap <name>
or specularMap <name>

// RMO packed material map (must have same image dimensions as the map provided)
// <red channel> roughness map
// <green channel> metalness map
// <blue channel> occlusion map
// <alpha channel> specular scale map (only when using rmosMap)
rmoMap <name>
or rmosMap <name>
  
// ORM packed material map (must have same image dimensions as the map provided)
// <red channel> occlusion map
// <green channel> roughness map
// <blue channel> metalness map
// <alpha channel> specular scale map (only when using ormsMap)
ormMap <name>
or ormsMap <name>
  
// MOXR packed material map (must have same image dimensions as the map provided)
// <red channel> metalness map
// <green channel> occlusion map
// <blue channel> specular scale map (only when using mosrMap)
// <alpha channel> roughness map
moxrMap <name>
or mosrMap <name>
  
// change the stages BRDF to look more like fabrics
// just need to provide the keyword like glow or detail
cloth

Here is a simple example of a gold shader that doesn't use any texture:

textures/rend2/Gold
{
	{
		map $lightmap
	}
	{
		map $whiteimage
		specMap $whiteimage
		rgbGen const ( 0.0 0.0 0.0 )
		specularScale 0.8 0.466807 0.254887
		roughness 0.5
		blendfunc GL_DST_COLOR GL_ZERO
	}
}