[c2 patch] MRUMemoryStore extension

[Gerhard Froehlich <g-...@gmx.de>]

Hi Team,
here is the MRUMemoryStore extension.
Following changes:
1. Objects (CacheEventObject, CacheStreamObject, ComponentCacheKey,
CacheValidity) can
be stored in a persitent state on the filesystem(workdir), if configured in
the cocoon.xconf file.
2. When storing a object in the MRUMemoryStore, it will be automatically
pushed on a stack. The stack is asynchron processed by a background thread,
which finally serialize the objects. The interval of this thread and its
priority can be configured in the cocoon.xconf.
3. When getting a object the store first checks memory, then the filesystem
if first fails.
4. In the FilesystemStore class every file name is encoded by the
java.net.URLEncoder.
5. The CacheEventObject, CacheStreamObject, ComponentCacheKey, CacheValidity
know implementing(extending) the java.io.Seriazable interface.

If you have some troubles with the new patches, you can switch off the
filesystem storing in the cocoon.xconf. Then the MRUMemoryStore executes in
the old way.

Please take a look in the cocoon.xconf.

Have fun (I hope :-)).
Suggestions and critics wanted...

Cheers
Gerhard