Log Message:

Update to 0.15.1

  FIX: in version 0.15.0 mkc.subprjs.mk was added, but it was not
      installed because I forgot to add it to Makefile. Now it is
      installed just like all other *.mk files.

  FIX: 'all : errorcheck' is not for bsd.subdir.mk and bsd.subprj.mk

  mkc.subprjs.mk has been renamed to mkc.subprj.mk.
  mkc.subprjs.mk is installed as a symlink.