Add support for inputs and outputs

Support ports from param.cgi
Support port.cgi for control
Support IO port event, Supervised input event and Relay event

Improve event system

Split event into services and stream
Event signalling now signals event name rather than event object
Move event information into event classes
Move event stream configuration into stream manager

Standardized API management and new APIs

Standardize how to work with different API endpoints
Add support for user management from pwdgrp.cgi
Improve parameter management by replacing the Vapix param management with a dedicated param.cgi implementation

Events can now remove callbacks

v20

Bump to v20

No debug prints in production code

v19

Bump to v19

Allow connection status notifications

Simplify configuration, break out event config.
Simplify event handling by managing outside of stream manager

Simplify event management

v17

Bump to v17

Improved error handling

v16

Bump to v16

v14: Merge pull request #3 from Kane610/async_rewrite

Bump to v14

Async rewrite

Merge pull request #1 from Kane610/async_rewrite

Async rewrite