(bug 48145) Adding calendar hint message

Message informing about the calendar that is detected automatically when specifying a date.
The message will be shown only when the specified date lies within a time frame when multiple
calendars had been in use. Since only Gregorian and Julian calendar are implemented at the
moment, this is specifically implemented according to those calendars.
In addition to the plain message, a links allows switching between the currently implemented
calendars.

Change-Id: I8b3d2bb6c04b01fc987c2c4ed9c0bd406a824134
Merge "(bug 48145) Adding calendar hint message"