moc: Make error message 'too many input files' more verbose.

Make it easier to diagnose quoting errors in scripts.

Change-Id: I17894a426faa5cdf50f5ace4ed422ab2bd202558
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Fix nested template declarations for non-C++11 builds

Change-Id: Ie38aae09033a47106a4a1cf2e9997f90961a4e33
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>