Fix gtkD api display

[Johnson Jones via Digitalmars-d-learn]

https://api.gtkd.org

It is difficult to navigate.

1. clicking the documentation on the main site takes it to the 
gtk.AboutDialog api. That is all it shows, I was confused at 
first, as I'm sure most people would be.

2. The packages list lists all the packages, but all the sub 
elements are expanded, making it time consuming to hunt down 
anything specific. Initially collapsing them and adding a search 
box would be nice.

3. When clicking on any packages it reloads the page and shows 
only the package in the first tab. This requires one to then go 
back to packages and hunt for something else again. Because the 
position of the scroll is not saved, one has to scroll down 
through the entire list.

It would be better, I think, if it was one single tab all in a 
single hierarchy that never reloaded the page so that it is 
easier to navigate quickly.

e.g.,

instead of

Package
atk
   atk.ActionIF
   atk.Action
   ...

we have

atk
   atk.ActionIF
      GetActionStruct
      GetStruct
      ...
   atk.Action
      ...
...


and so effectually combining both tabs. It should solve the 
issues that the current way has without really causing any 
problems. Everything should be collapsed by default and since no 
reloading of the page should occur(which might require having the 
api descriptions in a separate frame that is loaded separately on 
package changes to avoid reloading the tree view which will 
recollapse everything).

It will make navigating the gtkD api much more fun ;)