add FM keyblank, and modify some modules to work with tip-stop keys

fm.scad

@@ -0,0 +1,27 @@
+use <keygen.scad>
+include <fm.gen.scad>
+
+bitting_code = "1526985";
+
+// The FM keyblank can be used in many key systems
+// This is the depth table for Best A2 system
+
+cut_locations = [for(i=[.080, .230, .380, .530, .680, .830, .980]) -i*25.4];
+
+depth_table = [for(i=[0.318:-0.0125:0.205]) i*25.4];
+
+heights = key_code_to_heights(bitting_code, depth_table);
+
+difference() {
+    key_blank(outline_points,
+              warding_points,
+              outline_paths=outline_paths,
+              engrave_right_points=engrave_points,
+              engrave_right_paths=engrave_paths,
+              engrave_left_points=engrave_points,
+              engrave_left_paths=engrave_paths,
+              offset=[-outline_points[103][0], -outline_points[96][1]],
+              milling_offset=30,
+              plug_diameter=10.8712);
+    key_bitting(heights, cut_locations, .7874);
+}