This is a breaking change to the WebSockets layer to align it with
recent specification documentation work.
To support this, HAL SimValue changed readonly to a direction enum.
This allows specifying bidirectional in addition to input and output.
The SimValue change is specifically designed to avoid API and ABI breakage.
This is completely transparent in C++; in Java a new callback class was added,
and the old readonly functions have been marked deprecated.
A new SimValue creation function for enums allows specifying double values
for each enum value, not just strings. This allows mapping enum values to
doubles in the WebSockets layer.
A ":" in the SimDevice name now maps it to different WebSocket types (e.g.
"Accel:Name" becomes type "Accel", device "Name"). The type is hidden
in the GUI.
Other WebSockets changes:
* Implemented match_time and game_data
* Added joystick rumble data
* Added builtin accelerometer support
* SimValue enums are mapped to string and double value on WS interface
* Added WebSockets protocol specification
* Added READMEs
This allows high-level library classes to implement enhanced simulation
support even if no low-level corresponding simulation library exists, and
avoids the need for bit-banging complex interfaces like SPI or CAN.
