* ext.tex: documentation for extending, reference counts, and embedding

* ext.tex: documentation for extending, reference counts, and embedding
  (formerly ../misc/{EXTENDING,REFCNT,EMBEDDING}).  Also affects Makefile.
* text2latex.py: script to do part of the conversion from an plain ASCI
  text file (in my particular style) to LaTeX.
  (Chapter/section/subsection headers, and verbatim sections.)
* partparse.py, texipre.dat, fix.el, Makefile: Minor cleanup of latex ->
  info conversion process (at least it works again, and with less
  debugging output).  Removed fix.sh.
* lib1.tex (section{Built-in Functions}): adapt description of str() and
  repr() to new situation.
* lib3.tex (Module os): added exec*() variants.
* lib3.tex (Module posix): added execve().
* lib2.tex (Module array): documented reality; remove typecode and
itemsize, add byteswap, rename read/write to fromfile/tofile, and
re-alphabetized.
* lib1.tex (Built-in Functions): renamed bagof() to filter().