New component BorderedComponent

The BorderedComponent groups all components which feature a regular Border. The BorderedComponent as well as the WindowPane (which does not have a Border but a FillImageBorder instead) features furthermore BoxShadow and CornerRadius which was previously limited to Button and ListComponent.

Limitations:

Due to a restriction in the HTML specification rounded corners are not rendered in conjunction with the border-collapsed attribute set to 'collapsed'. This restriction applies to the Grid and Table component:

![image](https://f.cloud.github.com/assets/3050757/758549/18eb20f0-e73d-11e2-8dbc-5a260d8822e1.png)

So currently it is recommendable to use either radius *or* border but not both features together.

A possible alternative has been outlined at:

http://www.mediaevent.de/2012/08/html-table-border-radius-border-collapse/

In any case this would require a major redesign (such as using divs with table display) which I wanted to avoid for now. In that context the concept of a common border (for inside *and* outside the Grid/Table) should be revised. IMHO we should introduce an inner border distinct from the general (outer) border.