Check if the account is enabled at login

Not used yet, but possibly will be in the future.
Refactored backend server a little
Use get_ip to get consistent IP address from data

This is to ensure that all functions that get an IP are getting the same
kind of data (that is, an integer with the bounds of a signed 32 bit
integer) for consistency purposes.
Modify the keep alive for QR
Merge branch 'master' of https://github.com/polaris-/dwc_network_server_emulator