enhance resource filtering

Something discussed on the dev/user lists recently, and an initial implementation is in place. Here is my proposal from the list:

I would like to propose a generic solution via the POM and whatever filter-enabled copying technique that is being used. Let me know what you think.

Firstly, inside <build>:
<filters>
<file>$

/conf/filters.properties</file>
<file>$

/../common/filters.properties</file>
<filter>
<token>some.property</token>
<value>some.value</value>
</filter>
</filters>

Or to go really crazy, have the above as a filterset, and wrap them up in a list of filtersets. Ant introduced this functionality, but personally I don't see the use for it as long as you keep your property names a little different.

I also think build.properties, project.properties and driver/default.properties should be included by default when filtering is enabled.

Now, each <resource/> element can keep the <filtering>true</filtering> property to acknowledge it wants to be filtered.

The reason to allow different files is that the purpose of filters is to be able to substitute varying values, so you may not want to hard code them into project.xml. And this configuration should be flexible enough to work without Ant if necessary.

I'm happy to work on this once there is agreement - just opening this to track its progress.