Fix clamping of the minimum hash size, because the Melchior discovered

Fix clamping of the minimum hash size, because the Melchior discovered
  that the column math goes wacky when lgalloced is allowed to be
  zero.
Augment the find() function to take a starting index.
Fix strc() to use a default index of zero.
Fix parser precedence of TOK_MINUS, so that "a-b-1" means (a-b)-1 and
  not a-(b-1).