Function: filereadstr
Section: programming/specific
C-Name: gp_filereadstr
Prototype: L
Help: filereadstr(n): read a raw line from the file attached to the
 descriptor n, opened for reading with fileopen. Discard the terminating
 newline.  Return 0 at end of file.
Doc: read a raw line from the file attached to the descriptor $n$, opened
 for reading with \kbd{fileopen}, discarding the terminating newline.
 In other words the line is read exactly as input, up to the
 next carriage return \kbd{\bs n}. By comparison, \kbd{fileread} would
 read a logical line, as assembled by gp's preprocessor (skipping blanks
 and comments for instance).
