Extension point for "skinning" web gui

[Nicklas Nordborg]

Extensions can already supply custom scripts and stylesheets at certain places in BASE. But there is no overall extension point that is active on every page. It would be nice to have a "skin" extension point that is just able to add javascript and stylesheet to all pages in BASE.

[Nicklas Nordborg]

(In [6596]) References #1886: Extension point for "skinning" web gui

Added extension point, action class and a simple reference factory implementation. The Page/Head/Body uses the extension to add script and stylesheets to the generated html.

[Nicklas Nordborg]

(In [6628]) References #1886: Extension point for "skinning" web gui

Wrote some documentation about the new extension point.

[Nicklas Nordborg]

(In [6632]) References #1886: Extension point for "skinning" web gui

Adding support for re-mapping images to images provided by the skins. Basic support is added to the FixedSkinActionFactor which can be given a configuration parameter <image-remap-dir> that points to a path in the extension JAR file that simply mirrors the BASE web server (eg. /images directory) and re-maps images that are found.

[Nicklas Nordborg]

(In [6648]) References #1886: Extension point for "skinning" web gui

Dynamic attribute was broken by [6632] that moved the skin action to it's own class since it did not implement the DynamicActionAttributes interface.