This reverts commit c5bea524.

This reverts commit 2e1e671d.

- main mplib rules located in GENERAL_RULES with specializations
  (if any) under RULES. Modest change in a few options files, but
  cleans up the rules directories.

  previously in options:
      include $(RULES)/mplib$(WM_MPLIB)

  now in options:
      sinclude $(GENERAL_RULES)/mplib$(WM_MPLIB)
      sinclude $(RULES)/mplib$(WM_MPLIB)

  For GNU make it would be permissible to write both in a single line.

- more consistent script names
- remove '-help' option from internal scripts

- simplified the logic
- provide direct link to the respective scripts
- provide help from the respective scripts

- place wmkdep and dirToString executables under
  utilbin/$(WM_ARCH)$(WM_COMPILER).
  This helps somewhat when copying rules about, and might help when creating
  general rules.