Added test for hexagonal cylinder orientation, aka. captured nuts

doc/TODO.txt

@@ -259,7 +259,6 @@ o variants of module transparent() { %child(); }
 o define modules
 o define functions
 o built-in variables and constants (builtin-tests.scad)
-o Write a regression test for the hexagonal cylinder orientation issue
 o Caching
   - Test that caching is actually performed (speedup + same results)
   - Test the modifier characters correctly influence the cache (also when

testdata/scad/features/cylinder-tests.scad

@@ -12,4 +12,9 @@ translate([22,-11,0]) cylinder(h=5, r=5, r1=0, center=true);
 translate([22,0,0]) cylinder(h=5, r=5, r2=0);
 translate([22,11,0]) cylinder(h=15, r=5, r2=5);
 
+// This tests for hexagonal cylinder orientation, since people
+// tend to "abuse" this for captured nut slots
+translate([-10,0,0]) cylinder(h=2, r=3, $fn=6);
+
+
 // FIXME: We could test $fs, $fa, $fn as well