Updated to latest Chrome/Safari/wsProxy.

[drgrussell]

• Works with wsproxy, though you must set the connection to binary using
  setProxyEncoding('binary');
• Updated to use the latest xterm.js
• Can do binary websockets
• Works again with the latest Chrome and safari (and maybe others!)\

Issues: #45 , #43 , #38
Probably #36 , #29 , #28

Long comments on the changes

css/xterm.css

• Updated css/xterm.css with xtermjs 4.11.0

css/main.css

• Some SSHy css had been added to the end of css/xterm.css previously, and this
  is now appended to css/main.css

js/xterm-addon-fit.js

• FIT is now seperate from xterm, so include FIT imported using npm and
  translated from typescript (then tidied).

js/src/xterm.js

• Updated to xtermjs 4.11.0. This is an npm import. Deleted the old
  version, which was originally called js/src/xterm.min.js

js/settings.js

• xtermjs renamed some variables and functions or made them private.
  "Themes" was one of those.
• The interface to FIT was also changed.

js/SSHyClient.js

• The interface to FIT was changed.
• Make sure the side panel is updated with row/col changes from FIT.
• Previously the ssh transport to the ssh server was fed from an event handler
  using onkeydown. This meant that the feeder also had to translate key
  events into xterm escape codes. This used a private function which is now
  inaccessible. The code was changed to mostly
  use the onData event from xtermjs, which does all the transation for you.
  We still use an event handler though to get the username and password, and
  switch to onData once the connection is authenticated. Rather than use
  onkeydown, we now use xtermjs attachCustomKeyEventHandler. This greatly
  simplifies the code too. The code for local echo was lost in the update,
  but I dont think that worked anyway.
• Code about pasting just doesnt work now. onPaste is triggered well after
  xtermjs processes the paste. So moved the Split code into onData to protect
  from any transmission of large blocks.
• Added in a way to switch on binary transfer mode. Made the default still
  base64. But now you can
  setProxyEncoding('binary');
  after loading the scripts to change to binary mode.
  It is much harder than it appears to do the string to arraybuffer
  conversion. Encode and decode do not work here.

fastbuild

• Just wanted to build libraries which were not minimised for development and
  debugging. This trivial script seems to do the job

wrapper.html

• FIT doesnt seem to work in ROWS when the enclosing DIV is not height:100%.
• Include main.css, as this is now split out of the imported xterm.css
• link has never supported async as far as I can see

index.html

• link has never supported async as far as I can see
• FIT doesnt seem to work in ROWS when the enclosing DIV is not height:100%.
• Could not test this properly in base64, as I could not build
  the old wsproxy which is in this distribution (too many out of date
  dependencies). But I tested some of it, and it seems to be
  right. Works fine with the latest wsproxy in binary mode
• You can do binary mode by calling
  setProxyEncoding('binary');
  This is the default here as it then works with the latest wsproxy
  It is much harder than it appears to do the string to arraybuffer
  conversion. Encode and decode do not work here.