FreeRDP build as library, embedded nodejs modules

• FreeRDP is now built as a dll instead of an executable for better modularity and to reduce the risk of false positive detection of wfreerdp.exe by some antiviruses (mostly cloud based)
• embedded interact.js and simple-keyboard (nodejs modules) into myrtille in order to remove dependencies on external CDNs (ans thus allow myrtille to be used standalone and not subject to external changes)
• fixed a problem with the creation of the self-signed certificate that prevented Myrtille from installing correctly on Windows Server 2012 R2 (thanks camjcorley)
• a session can now be shared directly by url (simply copy & paste the page url then share it), with owner rights (web.config, can be disabled for anti-spoofing protection)
• region updates are now dropped by the gateway if the client latency is above the image cache duration (1 sec); only fullscreen updates are sent
• display updates can now be distributed across concurrent websockets (round robin load balancing) to reduce lag in case of network issues (config.js, default 5 websockets: 1 up 4 down). CAUTION! IIS on Windows client OSes (7, 8, 10) is limited to 10 simultaneous connections only - across all http sessions - and will hang after that! use Windows Server editions for production environments
• the mouse move sampling rate is now decreased automatically in case of low bandwidth (default 100%, config.js)
• refactoring