Example for version use by builder
Add specs for Autoconf::Version
Add Builder specs
Bugfix: check for extension at the end of the file name
Correct method name
Update example project
Tweak debug messages
Simplify source file task definition
Distinguish File-type tasks from others
Correct dependency logic

Invoke compile before checking is target is needed.
In this way, target will not always be 'needed?' du to the
non-invoked compile prerequisite.
Check for all FileTask types