support pitch and roll

src/experimental/_impl/_lsystem3_impl.scad

@@ -19,9 +19,13 @@ function _next_t1(t1, t2, code, stack) =
 function _next_t2(t, code, angle, leng) = 
     is_undef(code) || code == "[" || code == "]" ? t :
     code == "F" || code == "f" ? turtle3d("xu_move", t, leng) :
-    code == "+" ? turtle3d("zu_turn", t, angle) :
-    code == "-" ? turtle3d("zu_turn", t, -angle) : 
-    code == "|" ? turtle2d("zu_turn", t, 180) : t;       
+    code == "+"  ? turtle3d("zu_turn", t, angle) :
+    code == "-"  ? turtle3d("zu_turn", t, -angle) : 
+    code == "|"  ? turtle3d("zu_turn", t, 180) :   
+    code == "&"  ? turtle3d("yu_turn", t, angle) :        
+    code == "∧"  ? turtle3d("yu_turn", t, -angle) :
+    code == "\\" ? turtle3d("xu_turn", t, angle) :             
+    code == "/"  ? turtle3d("xu_turn", t, -angle) : t;       
 
 // It doesn't use recursion to avoid recursion error.    
 function _lines(t, codes, angle, leng) = 

src/experimental/lsystem3.scad

@@ -7,6 +7,11 @@ use <turtle/turtle3d.scad>;
    f  Move forward without drawing a line
    +  Turn left
    -  Turn right
+   |  Reverse direction (ie: turn by 180 degrees)
+   &  Pitch down
+   ∧  Pitch up
+   \  Roll left
+   /  Roll right       
    [  Push current turtle state onto stack
    ]  Pop current turtle state from the stack