This is a Nautilus Actions private library.

This is so called just because headers are or may be required by public
Nautilus-Action API or by extensions who use this API.

It so appears a bit more cleaner to put the corresponding code just
besides of these headers, and to build with them a dynamic library.

It is called private because headers are installed as part of N-A
development, but should not be directly included by external extensions.
