OTHER: Fix python 3 compatibility
OTHER: Fix behavior of --with-builtin-plugins

Default builtin plugins would trigger an error if some was
disabled explicitly using --with-plugins or --without-plugins.

It now setup the default builtin plugins once selected plugins have
been setup to filter out disabled plugins.
OTHER: Let the compiler figure out what to inline.

No change in CPU usage on Linux, and skipping inline unbreaks
the build on Mac OS X.