Added support for GLSL 3 shaders (GLSL 3.30 and GLSL ES 3.00).

To use GLSL 3 in a shader, the first line of the shader has to be: #pragma language glsl3

glsl1 is the default language.

Added “glsl3” graphics feature as part of the table returned by love.graphics.getSupported().

Added love.graphics.validateShader(boolean gles, shadercode). It returns a boolean along with an error string if the shader code has errors for its target language and platform (gles or desktop).

Implemented support for Core Profile OpenGL 3.3 in love.graphics.

--HG--
branch : minor

src/modules/graphics/opengl/Shader.h

@@ -102,9 +102,6 @@ private:
 	// Get any warnings or errors generated only by the shader program object.
 	std::string getProgramWarnings() const;
 
-	// Source code used for this Shader.
-	ShaderSource shaderSource;
-
 	// Shader compiler warning strings for individual shader stages.
 	std::map<ShaderStage, std::string> shaderWarnings;