Add extension point for selecting start page

[Nicklas Nordborg]

After logging in to BASE the View->Home page is displayed. An extension point should be defined that let users select a different start page.

The BASE->Preferences... can be used to display a list of possible start pages.

[Nicklas Nordborg]

(In [7111]) References #1995: Add extension point for selecting start page

Defined the net.sf.basedb.clients.web.start-page extension point and the StartPageAction interface that should be implemented by extensions. The FixedStartPageFactory is a simple action factory that creates a static start page from configuration options in the extensions.xml file.

[Nicklas Nordborg]

(In [7112]) References #1995: Add extension point for selecting start page

Added configuration setting in the BASE -> Preferences dialog for selecting the start page.

[Nicklas Nordborg]

(In [7113]) References #1995: Add extension point for selecting start page

Added StartPageBean which can be useful for extensions to this extension point.

The start page URL may contain $SESSION-ID$ as a placeholder for the current session id.

[Nicklas Nordborg]

(In [7114]) References #1995: Add extension point for selecting start page

The login handling should now support this feature. It is available from the main login page and from the "Switch user" dialog when the "Remain on this page" is not checked. The login page that is shown after an automatic logout due to a timeout does not support this feature since it may interfere with what the user doing.

A concern is that the new start page doean't exists or has an error of some sort. In this case it may result in a lockout of the user. To prevent this a special page for handling "404 Not found" errors have been created. This page should display the regular BASE menu and allow the user to continue and modify the start page setting.

If this doesn't work it is also possible to hold down CTRL or ALT or SHIFT while clicking on the "Login" button. This will disable the extension start page and always display the regular home page instead.

[Nicklas Nordborg]

(In [7115]) References #1995: Add extension point for selecting start page

Updated documentation with information about this feature.

Also noted that the "Remember dialog positions" (#1825) feature was not documented and added a short text about this.

[Nicklas Nordborg]

All tests have now been completed successfully.