big function re-org to eliminate debug.scad and hide affine.scad from docs

arrays.scad

@@ -1985,4 +1985,29 @@ function is_matrix_symmetric(A,eps=1e-12) =
     approx(A,transpose(A), eps);
 
 
+
+// Function&Module: echo_matrix()
+// Usage:
+//    echo_matrix(M, [description=], [sig=], [eps=]);
+//    dummy = echo_matrix(M, [description=], [sig=], [eps=]),
+// Description:
+//    Display a numerical matrix in a readable columnar format with `sig` significant
+//    digits.  Values smaller than eps display as zero.  If you give a description
+//    it is displayed at the top.  
+function echo_matrix(M,description,sig=4,eps=1e-9) =
+  let(
+      horiz_line = chr(8213),
+      matstr = matrix_strings(M,sig=sig,eps=eps),
+      separator = str_join(repeat(horiz_line,10)),
+      dummy=echo(str(separator,"  ",is_def(description) ? description : ""))
+            [for(row=matstr) echo(row)]
+  )
+  echo(separator);
+
+module echo_matrix(M,description,sig=4,eps=1e-9)
+{
+  dummy = echo_matrix(M,description,sig,eps);
+}
+
+
 // vim: expandtab tabstop=4 shiftwidth=4 softtabstop=4 nowrap