[BUG] Slider anchors are incorrect

[Skinner927]

Describe the bug

1. slider()'s anchor box is rotated 90 degrees, too tall (Z) and not wide enough (X).
2. slider()'s default spin should match rail().

Code To Reproduce Bug

include <BOSL2/std.scad>
include <BOSL2/sliders.scad>

slider() show_anchors();

right(40) rail() show_anchors();

Expected behavior

Anchors should lay correctly on slider() and it should be oriented the same as its matching rail().

Fix

I can make a PR if you prefer.

--- a/BOSL2/sliders.scad
+++ b/BOSL2/sliders.scad
@@ -38,12 +38,11 @@
 function slider(l=30, w=10, h=10, base=10, wall=5, ang=30, anchor=BOTTOM, spin=0, orient=UP) = no_function("slider");
 module slider(l=30, w=10, h=10, base=10, wall=5, ang=30, anchor=BOTTOM, spin=0, orient=UP)
 {
-    full_width = w + 2*wall;
+    full_width = w + 2*wall + 2*get_slop();
     full_height = h + base;

-    attachable(anchor,spin,orient, size=[full_width, l, h+2*base]) {
-        zrot(90)
-        down(base+h/2) {
+    attachable(anchor,spin,orient, size=[full_width, l, full_height]) {
+        down(full_height/2) {
             // Base
             cuboid([full_width, l, base-get_slop()], chamfer=2, edges=[FRONT,BACK], except_edges=BOT, anchor=BOTTOM);