Improve Database listing

[tbussmann]

We do currently list all databases in the GUI that accept connections (datallowconn) and order them alphabetically. The first one is selected.

I'd like to suggest two improvements:

1. show the template databases (datistemplate) with a dimmed icon. Eventually include postgres as well.
2. automatically select the database that is named after the current user

If you are new to PostgreSQL, you will likely not know what the template1 or postgres database is for. Showing them all in an equal way makes it harder than necessary to decide which to connect to, esp. if your username starts with a letter > p or t.

[tbussmann]

from #790 : typing in the database view to select an entry starting with that name