Backwards compatible rotate_extrude for OpenSCAD with angle parameter

rotate_extrude2.scad

// older versions of OpenSCAD do not support "angle" parameter for rotate_extrude
// this module provides that capability even when using older versions (such as thingiverse customizer)
module rotate_extrude2(angle = 360, convexity = 2, size = 1000) {
	module angle_cut(angle = 90, size = 1000) {
		x = size*cos((angle / 2));
		y = size*sin((angle / 2));
		translate([0, 0, -size]) linear_extrude((2 * size)) polygon([[0, 0], [x, y], [x, size], [-size, size], [-size, -size], [x, -size], [x, -y]]);
	}
  // support for angle parameter in rotate_extrude was added after release 2015.03
  // Thingiverse customizer is still on 2015.03
  angleSupport = (version_num() > 20150399) ? true : false; // Next openscad releases after 2015.03.xx will have support angle parameter
  // Using angle parameter when possible provides huge speed boost, avoids a difference operation
	if(angleSupport) rotate_extrude(angle = angle, convexity = convexity) children();
	else rotate([0, 0, (angle / 2)]) difference() {
		rotate_extrude(convexity = convexity) children();
		angle_cut(angle, size);
	}
}