Add file with many abbreviated commands.

include/short.scad

+module tX(x) { translate([x,0,0]) children(); }
+module tY(y) { translate([0,y,0]) children(); }
+module tZ(z) { translate([0,0,z]) children(); }
+module tXY(x,y) { translate([x,y,0]) children(); }
+module tXZ(x,z) { translate([x,0,z]) children(); }
+module tYZ(y,z) { translate([0,y,z]) children(); }
+module tXYZ(x,y,z) { translate([x,y,z]) children(); }
+
+module rX(x) { rotate([x,0,0]) children(); }
+module rY(y) { rotate([0,y,0]) children(); }
+module rZ(z) { rotate([0,0,z]) children(); }
+
+// operations
+module diff() {
+    difference() {
+        children(0);
+        // step needed in case $children < 2
+        for (i=[1:1:$children-1]) children(i);
+    }
+}
+
+module tube(l, th) {
+    linear_extrude(l) diff() {
+        offset(2*th) children();
+        children();
+    }
+}