v4.0.0-beta.1

Add Mac Support!

• Switch to WinHttpRequest (Modern alternative to ServerXMLHTTP)
• "Freeze" Request on execute (multiple requests with same Request don't interact)
• Remove deprecated code
• General VBA compatibility
• Separate Async behavior into separate Class

Some changes (possibly breaking) are likely to come before hitting v4.0.0, so this beta is only suitable for testing