Added various functions basic math classes. Also enabled math checks only for debug builds.

Added set_scale, set_rotation_euler, set_rotation_axis_angle. Addresses #2565 directly.
Added an euler angle constructor for Basis in GDScript and also exposed is_normalized for vectors and quaternions.
Various other changes mostly cosmetic in nature.

core/math/quat.cpp

@@ -91,6 +91,10 @@ Quat Quat::normalized() const {
 	return *this / length();
 }
 
+bool Quat::is_normalized() const {
+	return Math::is_equal_approx(length(), 1.0);
+}
+
 Quat Quat::inverse() const {
 	return Quat(-x, -y, -z, w);
 }