silent rules and warnings

[John W. Eaton]

I checked in a series of changes that reduced the number of warnings in 
the build.  For my build on a Debian system, I only see a few warnings 
now.  I'd like to eliminate all of them, but there are a few from code 
generated by flex that I see no easy way to eliminate.  In any case, my 
hope is that we can prevent any new warnings from appearing and keep the 
build clean.

I also checked in a change to make the --enable-silent-rules configure 
option much more useful.  Perhaps we should enable this by default?  The 
terse output of silent rules used to annoy me because I never seemed to 
be able to figure out how to get the full command output when it was 
needed for debugging.  But with Makefiles generated by automake, it is 
as simple as passing V=1 to make.  So I don't really see a downside of 
enabling silent rules by default for all builds.  The big positive 
benefit for me is that warnings and errors are much more visible and it 
will be more obvious when some code is added that accidentally produces 
a warning.

Is there any objection to enabling silent rules by default?

jwe