Server: With -daemon, disable standard output

The server is headed towards being a background process; for now,
the -daemon option is used when the server is started in background
mode.
libshell: Improving dialog closing

Derived classes may override the dialog post-processing function.
libdeng2|Network: Opening a socket to a host identified by domain name

de::Socket now has the ability to look up the IP address of a domain
name in its non-blocking connectToDomain() method.

Also applied the pimpl idiom in de::Address.
libshell: Removed unnecessary TextWidget::setRule()

Replacing a widget's rule rectangle instance is not very useful.
Shell: Opening and closing the connection to user-provided address