Use named variable instead of array in Platform.openTerminal()
Use named variable instead of array in Platform.openFTPBrowser()
Inline SocketUtils.LOCALHOST constant
Use ProcessBuilder to open terminal emulator

TODO: replace Runtime.exec() in other places
Extract class Putty to remove code duplication
Pass params map to Platform

It's better to let a Platform instance manage which options to use
instead of preparing options in Backend class.
Use ProcessBuilder everywhere
Always negotiate telnet options (seems to work fine)