TODO

 * Improve error/warning messaging when parsing configuration file

 * Consider reworking line toggle and line pulse featueres in case requests are made to apply them to more lines:

     ctrl-t g Toggle serial line
     
     Which would then make tio ask which line to toggle:
     
     [20:50:11.691] Please enter which line number to toggle?
     [20:50:11.691] DTR(0) RTS(1) CTS(2) DSR(3) DCD(4) RI(5)
     
     ctrl-t p Pulse serial line
     
     [20:50:11.691] Please enter which line number to pulse?
     [20:50:11.691] DTR(0) RTS(1) CTS(2) DSR(3) DCD(4) RI(5)
     
     command-line:
     --line-pulse-duration="DTR=60,RTS=50,CTS=40,DSR=30,DCD=20,RI=10"
     
     config file:
     line-pulse-duration="DTR=60,RTS=50,CTS=40,DSR=30,DCD=20,RI=10"