subroutine peptin  --  j.f.chandler  august 1978
cms interface added 1980 dec
this routine reads cards from the input stream until it
encounters a *include card.  then it reads from the requested
external source file either until the end or an optional
maximum number of card images.  anyway, it then switches back
to the usual input stream.  note: a *include found within an
external source file has the same effect as one in the
primary input stream except that it causes an immediate end of
that file, that is, there is no push-down facility.  any
errors in syntax or missing files or i/o errors on external
source files are noted and tallied in 'error'.  the syntax:
*include ddname(member)
there is another format available for cms files:
*include 'name type mode'
the ddname or fileid may begin in any column up to 16.