1. The plugin will have a function char * getMetadata() in the vTable.
   - this XML metadata will contain all (plugin and option) metadata.
2. libcompiz will have a function that creates a CompMetadata object
   - There will be functions like char * getOptionShortDescription( CompMetadata *d, CompOption *o)
3. There will be a function that can merge two CompMetadata objects into one
   - this will allow us to include updated/extended/translated metadata (read from a file) into a plugin

Layout
<metadata>
	<plugin name="xxx">
		<short>XXX</short>
		<long>XXXX</long>
		<author>XX XX</author>
		<version>0.1</version>
		<value key="foo">bar</value>
		<value key="foo2">bar2</value>
		<screen>
			<option name="raise_on_click">
				<short>...</short>
				<long>...</long>
				<value key="group">...</value>
				<value key="subgroup">...</value>
				<value key="...">...</value>
			</option>
		</screen>	
		<display>
			.....
		</display>
	</plugin>
</metadata>