MBS Filemaker Plugin, version 2.7pr1

New in this prerelease of the 2.7 plugins:

Added PDFKit.GetPDFPageFormattedText function.
Changed Webview and Window functions on Mac so they better check if a handle is no longer valid. We now track which windows are closed and invalid window references so they can't be used.
Changed plugin to use more Unicode APIs for better file name handling.
Added functions Files.AppPath, Files.Launch, Files.LaunchFile and Files.RevealFile.