(sctstr): Member sct_che encoded number of che and their target.

Simplify.  Split into member sct_che (number) and sct_che_target.
Users changed.
(get_che_cnum, set_che_cnum, get_che_value, get_che_value): Che
encoding/decoding functions; remove.
(CHE_MAX): Move from var.h to sect.h.
(prsect, doland): Print / edit the new field.

src/lib/common/bridgefall.c

@@ -166,4 +166,5 @@ knockdown(struct sctstr *sp, struct emp_qelem *list)
     sp->sct_pstage = PLG_HEALTHY;
     sp->sct_ptime = 0;
     sp->sct_che = 0;
+    sp->sct_che_target = 0;
 }