Allow shader arrays to be passed as parameters and return value in functions

[Chaosus]

This PR significantly improves shader arrays by allowing them to be really passed to and from functions. Also, I refactored few methods for better functionality with them.

For example, such code will now behave correctly:

shader_type spatial;

struct Cool {
	vec3 v[2];
};

vec3[2] test(vec3 a[2]) {
	a[0].g = 0.0; // modify array inside function
	return a;
}

Cool[2] cool_test(Cool a[2]) {
	return {Cool({vec3(0.0, 0.0, 1.0), vec3(1.0, 0.0, 0.0)}), Cool({vec3(0.0, 0.0, 1.0), vec3(1.0, 0.0, 0.0)})};
}

void fragment() {
	// passing array to function "in-place"
	vec3 v[2] = test(vec3[2](vec3(0, 1, 0), vec3(1, 0, 0)));
	
	// assignment to existed array
	v = test({vec3(1, 1, 0), vec3(1, 0, 0)});
	
	// ternary operator
	bool t = true; 
	vec3 v3[2] = t ? v : test(v);
	
	// a complex assignment
	ALBEDO = v3[0] + cool_test({Cool(v), Cool({vec3(0.0, 0.0, 1.0), vec3(1.0, 0.0, 0.0)})})[0].v[0];
}

[akien-mga]

Thanks!