Function: writetex
Section: programming/specific
C-Name: writetex
Prototype: vss*
Help: writetex(filename,{str}*): appends the remaining arguments (same format as
 print) to filename, in TeX format.
Doc: as \kbd{write}, in \TeX\ format. See \tet{strtex} for details:
 this function is essentially equivalent to calling \kbd{strtex} on remaining
 arguments and writing them to file.
