dwt-addons rework, please test

[Frank Benoit]

I did a rework of the use of collections and added a new collection 
wrapper. The new wrappers make use of the new tango.util.containers 
instead of the prior code that used tango.util.collection directly.

The new collection wrappers in dwtx.dwtxhelper.Collection have still 
many unimplemented methods. If such one is called, the application is 
terminated immediatly with a message of file and line.

I did a few tests with examples to catch many of the unimplemented 
methods. If you encounter such a messages

implementation missing in file 
../dwt-addons/dwtx/dwtxhelper/Collection.d line 1527

please report that so the implementation can be added quickly.
Or if you want you can also send me patches or hg bundles :)