minor, AC_ARG_VAR MATLABPATH variable to allow customised setting
minor, AC_ARG_VAR OCTAVEPATH variable for symmetry
Merge branch 'contrib/mex-tzconv'

* contrib/mex-tzconv:
  minor, AC_ARG_VAR OCTAVEPATH variable for symmetry
  minor, AC_ARG_VAR MATLABPATH variable to allow customised setting