ProjectId, CurrentTab and CurrentSelection should be encoded in the browser URL

[matthewhorridge]

In order to support back/forward navigation with the browser, the current place needs to be encoded in the browser URL. The following should be encoded:

• Current projectId (it already is)
• Current tab selection. Not at the moment.
• Current object (entity) selection. Not at the moment.

Ultimately,

• The tabs need to be replaced with views which correspond to places (driven by what is at the moment the current tab selection). The tab bar then just becomes a link bar. (This would also support the lazy loading of other tabs).
• The current selection mechanism needs to be replaced and tied to browser history.

All of this will be doable when we replace GWT-Ext with regular/native GWT UI stuff.

[matthewhorridge]

Done in 3.0.0.