1.0.16.26: dx allocation thru CAST nodes

1.0.16.26: dx allocation thru CAST nodes

 * Allow DX allocation of LVARs thru cast nodes without type checks.

 * Since it is not obvious to me that all uses of CAST-VALUE must be
   in the same component as the cast itself, AVER that.

 * Results of MAKE-ARRAY can once more be stack allocated. Regression
   caused by different handling of TRULY-THE introducing cast nodes
   where there previously were none.

 * Tests.