Remove plot.gif files from repository

These were committed by accident.
Fix formatting
Fix multiple inheritence bugs
Work around low timestamp resolution on various platforms

HGFS+, ext3, and FAT32 are common file systems which have
relatively low timestamp resolution.  Some build systems,
such as GNU Make and Ninja, rely on modification times to
detect changes.  Changes were not being detected in some
cases for these build systems.  Work around by waiting to
make changes until the timestamps are distinguishable.
Add incremental build tests with fixed workload