Connect / Disconnect functionality

New functionality for opening and closing arduino board connections.  It includes 2 buttons in the arduino block group (one for connection and other for disconnection).

It offers several messages for giving feedback to the user and detects if the cable has been disconnected (for this it is required a recent version of the serialport module ... which does work on Mac but not yet on other platforms).

Adds multi language functionality (language files are like s4a-lang-es.js)