[alpha] First Release

Choose your installer:

• Slim installer. This works on Windows 8 and later. If you don't have Webview2 installed, then a bootstrapper will be downloaded.
• Main installer. This contains a bundled Webview2 bootstrapper. Windows 7 users should choose this installer as it works better.
• Webview installer. This contains an offline Webview2 installer with a relatively large package size.