Configurable spacing

[Rune Zedeler]

Hopefully the subject hasn't been totally forgot.
Generally 1.5 produce wider scores than 1.4 - often I need to use 1.4 
simply because the spacing in 1.5 is too so that the music doesn't fit 
in a decent amount of staff-lines.

Btw, what is the general opinion on convert-ly. How much does it need to 
convert? I.e. does it need to convert artihmetic-basicspace settings, or 
should it just produce a warning and a reference to documentation of how 
to perform the changes manually?

-Rune