Default Style - `.floating`

Changed the default style to floating.

It was supposed to be floating originally, something must have been missed.

RTM State Public

Able to access the RTM state, including offline state from AgoraVideoViewer

Extension Methods Public

This update makes the extension marketplace helper methods accessible.

Fixes #46

No buttons, no bar

• Button bar hides when there's no buttons
• RTM creation to utility thread
• rtmEnabled option added to AgoraSettings

Hide Button Bar

Button bar will not show at all if there are no buttons to show (video control buttons)

RTM to utility thread

RTM initialisation was blocking the video calling thread, this patch moves the initialisation so that video is not interrupted

Optional RTM

Use AgoraSettings property rtmEnabled to disable RTM in the UIKit project

Delegate Calls

• Add Delegate method calls from 1.6.4
• Add setting to hide your local camera feed

Public RTM Methods

• Make the RTM methods public

Better Delegate Method Access

• Additional way to access all delegate methods
• Add setting to hide your local camera feed
• Fixed compile time if statements' else's to check macos, rather than just 'else'