#105 Open database without closing current one

[U. Windl]

Say you have one database per CA (like a Host CA and a User CA). You open xca and open the first CA, then you need to open the second CA.
Currently opening a database automatically closes the current open database.

Wouldn't it be nice if the other database would be opened in its own windows (just as most office products do open files)? Along with this change the name of the database could go into the windows title also (currently there is the long product name and the short host name in it).

This change would make moving entries between databases much easier.
(Using xca 2.3.0)