InheritancePlugin bug in jobs without any parameters.

A null pointer exception was thrown in these cases.
Fixed issue with non-existing references resetting to default.

Now, the old value can be kept around; as the plug-in will detect
missing projects anyway.
Added table that shows last builds sorted by build time.

Additionally, the History is hidden when a project is not buildable AND
has no prior builds.

Fixed issue with the readOnly field not being set right.
This caused parent-references to be always read-only.
Fixed font width issues for SVG rendering.
Fixed SVG arrow head calculation.

Inverted arrows to reflect inheritance.

Also fixed issue with attachment point (SVG) being wrong.
SVG Graph now honours order of inheritance.

Made connection arrows appear behind boxes.
Fixed issue with build version links being wrong.

The "versions used" links were wrong on a Build's page. They failed
as soon as a URL-context was set.
Redirect triggered for rebuilding ignored the URL-context.
Replaced windows line-endings.