Maybe version should be mandatory

[Michael Kallas]

Would it maybe make sense to make \version 
numbers in the .ly files mandatory?
Or at least have some --Wall / --strict feature 
that fails if it is not set?
That way, you would't forget to insert the version 
and have to learn the hard way after years 
that it would have been good to do so for compiling 
with a different version.

Just a thought
Michael