Finally! The new identities plus a nice shiny settingspage for editing them are done!

The dialog should be fully functional, and you should be able to create/edit/save identities.
However, they are not yet actually used (which is why we still have the old dialog as well)...

Also I revamped the whole SettingsDlg stuff, it now notices when settingspages have changed
and behaves accordingly, you can reset/reload settings and whatever else you'd expect from a
fully functional configuration dialog...

Furthermore, I did some general prettyfication, added some icons, tooltips, whatsthis-texts
and so on.