GCC-3.1.1 fixes

GCC-3.1.1 fixes

* lily/include/stream.hh:
* lily/include/moment.hh:
* lily/include/midi-stream.hh:
* lily/streams.cc:
* lily/scm-option.cc:
* lily/parser.yy:
* lily/my-lily-lexer.cc:
* lily/moment.cc:
* lily/midi-stream.cc:
* lily/main.cc:
* lily/lexer.ll:
* lily/includable-lexer.cc:
* flower/include/source-file.hh:
* flower/include/parray.hh:
* flower/include/dictionary.hh:
* flower/include/array.icc:
* flower/string.cc:
* flower/source-file.cc:
* flower/getopt-long.cc: gcc-3.1 fixes.

* stepmake/stepmake/generic-targets.make: Add comment about warning.

* lexer-gcc-3.0.patch: Add comment, and a fix for installations
that have an unpatched flex and gcc-3.1.x.

* Documentation/topdocs/INSTALL.texi: Add comments and
instructions on gcc-3.1.x.

* lexer-gcc-3.1.sh: New file.

* aclocal.m4: regenerate.

* stepmake/aclocal.m4: Version compare fix.