NETWORK CREATOR SAVE/LOAD UPDATE
NEW: added network save/load in network creator
NEW: on exit attempt network creator asks to save the network if it was modified
NEW: network creator's title show network's name and whether it was modified since last save
CHANGE: improved printing network to console:
    - there is now no comma at the end of each line
    - there is now no line at the end of a list
    - next line character is now printed as "\r\n" instead of "\n"
BUGFIX: network creator does no longer crash when trying to generate statistics of empty network