Issue 4572: Remove the number of arguments from callback macros

The compiler is capable of counting the number of arguments in a callback.  It can also check that the number of optional arguments does not exceed the total number of arguments.

I've put the code that accomplishes these things in lily-guile-macros.hh, but it is generic enough that it might make more sense to create a new file for it.  Suggestions are welcome.

Changes in lily-guile-macros.hh are manual.  Everything else is automated with this script:

for FILE in $(git grep -l '^MAKE_[_A-Z]*SCHEME_CALLBACK[_A-Z]* ' lily)
do
    sed -i 's/\(MAKE_[_A-Z]*SCHEME_CALLBACK[_A-Z]*\) *(\([^,]*\), *\([^,]*\), *\([^,)]*\)/\1 (\2, \3/' $FILE
done

[dak, 2015-08-22 07:19:24]

That's overengineering in my opinion.  GUILE's own header macros take all the
given parameters so we get a discrepancy when LilyPond's equivalents don't do
so.

Unless there is a very compelling reason to indulge in this sort of thing (and
the template pokery-trickery in lily-guile-macros.hh is of unprecedented level
for what looks like rather immaterial gains), I'd strongly recommend not going
there.