BorderContainer support padding

[nonken]

To create a more solid L&F each bordercontainer which is using splitters as well should have a default padding with the bgcolor of the splitter. Using this padding the splitters will not end up in nothing but the BorderContainer?'s children will be embedded in the BorderContainer? resulting in an improved L&F. For BC elements not having a splitter you should be able to set that padding to 0

[nonken]

This BorderContainer? has a "padding" note the browser does not have a correct window size

[nonken]

Current BC style

[peller]

(In [13743]) Compute layout with padding. Fixes #6764 !strict

[nonken]

(In [13928]) removed default border on BorderContainer?, refs #6764

[nonken]

(In [13930]) set width/height to 100%, refs #6764

[nonken]

(In [13933]) fixed so BorderContainer? supports 100% width/height + padding, refs #6764 !strict

[nonken]

(In [13948]) fixed themeTester layout, Refs #6764

[bill]

(In [14414]) Fix non-portable code for padding calculations, refs #6764 !strict. This fixes mail demo editor layout problems in safari, refs #7096, #7097.

[bill]

(In [14419]) Oops, forgot node argument to _toPixelValue(). refs #6764 !strict.

[nonken]

Now BC doesn't have the padding anymore on bottom and left. check themeTester.html to see. Probably some regression

[bill]

Yah, I broke this but then fixed it above in [14419].