Further improve TeX output. The produced files are about 40%

Further improve TeX output.  The produced files are about 40%
smaller.  `lilyponddefs.tex' is now read only once.

* tex/lilyponddefs.tex: Remove footer stuff.
(\ifundefined): Renamed to...
(\lilypondundefined): This.  Use LaTeX's definition to
make it nestable and make it global.
(\lilypondstart, \lilypondend): New macro to initialize LilyPond
output.
(\lilypondspecial): New macro to read `music-drawing-routines.ps'.
(\fetasixteen, \fetafont, \fetachar, \botalign, \leftalign): Make
them global.
(\placebox): Renamed to...
(\lyitem): This.
Make it global and call \outputscale by itself.
(\lybox, \lyvrule): New macros to reduce input data.
(\lilypondfirst, \lilypondsecond, \lilypondloop, \lilyponditerate):
New auxiliary macros.
(\SkipLilydefs, \EndLilyPondOutput): Removed.
* tex/lily-pdf-defs.tex, tex/lily-ps-defs.tex (\lilySpace): Renamed
to...
(\lilypondspace): This and made it global.
(\turnOnPostScript): Renamed to...
(\lilypondpostscript): This and made it global.
(\turnOnExperimentalFeatures): Renamed to...
(\lilypondexperimentalfeatures): This and made it global.
* tex/lily-ps-defs.tex (\PSsetTeXdimen): Renamed to...
(\lilypondsetdimen): This and made it global.
* tex/lilypond-latex.tex, tex/lilypond-plaintex.tex: Removed.
* tex/GNUmakefile (TEX_FILES): Add `music-drawing-routines.ps'
(all, $(outdir)/music-drawing-routines.ps): New rules.
* buildscripts/mf-to-table.py (write_tex_defs): Use \gdef.
* scm/pdftex.scm, scm/tex.scm (end-output, header-end, placebox,
start-system, stop-system, stop-last-system, filledbox): Updated to
use the changed macros from lilyponddefs.tex.
* scripts/lilypond-book.ly (output_dict) <latex, texi>: Ditto.