Added "capply" methods to "array_md."

Added "capply" member function template to "array_md."  It is "apply,"
but always in 'const' mode.
Changed array creation functions.

Renamed "make_array" to "make_auto_array."  Reused "make_array" for
new, similar function that requires the return element type and
extent list to be specified.  Added function template "reshape_array"
that copies the elements of a given "array_md" object to one with the
specified element type and extent list.