This is the plugins implementation for Bacula.
The current plugins for the DIR and SD are untested.
For the File daemon, there are three plugins.  The
first is purely experimental. The second is quite functional
and useful -- bpipe, and the third is the Exchange plugin

For more details on plugins please see the New Features
chapter of the Concepts document.

What is implemented:
- load a plugin
- get main entry points in plugin (two)
- pass plugin Bacula entry points
- get plugin's entry points
- keep list of plugins that are loaded
- The plugin currently only needs config.h and bc_types.h
  in the Bacula src directory to be build.  Otherwise, it is
  totally independent of Bacula.
- The main test program is intended to be integrated into
  Bacula (at least a number of the functions therein).
- Search for all plugins in the plugin directory
- Implement Bacula context for plugin instances
- Implement plugin context for plugin instances
- Integrate the code into Bacula
- Figure out a way to deal with 3 types of plugins (Director,
  File daemon, Storage daemon).
- Pass Version information in plugin Initialize
- Document the interface
- Test Win32 plugins
- Print all plugins loaded when Bacula starts
- Print all plugins loaded during traceback
- Make libbac.a into a shared object and allow plugin
  to call functions in directly so that plugins can use
  the same "safe" system utilities that Bacula uses.
- Document libbac.so (when implemented)
- Write more plugins that really do something.
- Error handling must be much improved and brought into Bacula
  programming style. It currently just printf()s a message then
  exits (partially done).

What is not yet implemented:
- Implement plugin license/version checking
- Some better method to pass variables
- Define more functionality (Bacula entry points, ...)
  especially for DIR and SD plugins