* Documentation/windows/zlily-profile.sh:

* Documentation/windows/zlily-profile.sh:
* Documentation/windows/post-lilypond.sh: Assume normal
prefix=/usr for lilypond.

* lily/musical-request.cc (length_mom): Display origin with error.

* lily/lily-guile.cc (ly_pair_p): [PARANOID]: Check for freed
cells.

* lily/part-combine-music-iterator.cc (get_state): Bugfix: use
ly_symbol2scm to get a scm symbol (rather than ly_str02scm).

* aclocal.m4:
* autogen.sh: Regenerate.

* Documentation/topdocs/INSTALL.texi:
* configure.in:
* stepmake/configure.in:
* stepmake/aclocal.m4: Revert autoconf upgrade.  Autoconf 2.53 has
a serious bug wrt AC_CONFIG_AUX_DIR (reported).  Creating
./configure once again requires autoconf == 2.13.

* stepmake/autogen.sh: Check for autoconf == 2.13.