fix comment headers #327
changed scons to stop "installing" plugins to dev dir #355
moved plugins to lib64/plugins within tarball closes #355
added ProcessInfo::getExePath() #352

This gets the path of the current running binary.  The plugin autoloader
uses this to find the default plugins dir, a relative path from the
binary.

The linux2 implementation works, the others are hopeful attempts but
might not.
added a plugin autoloader #352

On startup, we look at all lib*.so files in a directory (default is
$(dirname <binary>)/../lib64/plugins, which is where the plugins get
installed in the tarball) and try to load them as plugins.

closes #352
added check for world writable plugins dir #357

Don't autoload anything from such a directory.
added check to refuse loading plugin if world writable #357

We currently have an implementation using dladdr() on linux to find the
real filename of the plugin.  We should make it portable at some point.
On FreeBSD at least, dlinfo() should work.

closes #357