(Bug 2150) Initial patch by 90d
(Bug 3150) Fix layout credit for custom layers

Custom layers with a system base will print
the theme and base name and link the base
category. Custom theme and base layer combos
will list name but not link. Custom base layers
only with use the notheme string from the
translation system and not link.
(Bug 2150) Initialize $layouturl
(Bug 2150) Remove spaces from variables and hardcode
(Bug 2150) Move spaces outside spans
Merge pull request #369 from momijizukamori/Bug2150/LayoutCredit

Adds layout and theme name to the credit module, and links the layout category if it's a system layout.