This directory contains the Drone plugins. Each plugin is contained in a separate 
directory with the name of the plugin, in the form
drone.<plugin_name>

Each plugin directory has the following structure:
build.xml  The plugin's Ant Build file
plugin.xml The plugin's JPF config file (not necessary for compilation)
src/       Contains the .java source files
build/     Contains the built .class files after building

To build a plugin:
cd drone.<plugin_name>/
ant

Ant will then built the plugin and put all compilation results in the "build" directory. 
Then it will make a jar file with name drone-<plugin_name>.jar and will put it in Drone 
distribution directory (which lies in ../dist/).

To build all plugins, just run "ant" from within the plugins directory.