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.

Feature has been tested with Chrome (very latest!, previous versions had issue with rounded border on select field), Firefox, IE8-10.