Use maps instead of vectors for holding strips and plugins
This allows to deal with "holes" after objects are removed
Also paves the way for a future improved way of identifying
individual strips and plugins
Terminology used by server and client was starting to diverge.
C++ classes ArdourStrips and ArdourGlobals classes have been
renamed to ArdourMixer and ArdourTransport respectively.
State node values for transport functionality have been simplified
and prefixed with 'transport_' to match what was done for strips.
Replace previous callback based basic client with an easier
to use object-oriented API that further abstracts the low level
details of the WebSockets Server surface messaging protocol.
All built-in web surface demos were updated to use the new API.
add methods to callback.js
automatically reconnect js client on disconnection
mixer-demo do not recreate UI on reconnection
NO-OP: indentation in message.js
make client JS reconnection optional
fix mixer-demo scrolling
minor JS client refactor
improve mixer-demo readability
"Always use Tabstops for block-indent (the code must be
formatted correctly with "[TAB] = N spaces" for any value of N).
Use space only for alignment." - https://ardour.org/styleguide.html
