Add Android Manifest to Allow Setting as Default Editor for MIME types ie text/plain text/x-csharp

[solutioneeer]

Current Android versions of Squircle-CE do not allow themselves to be assigned as the default file handler for most source code types. Apparently this is because an Android app has to explicitly state in a manifest component which MIME types it can handle, and the Android OS then uses that info to proffer which apps are 'suitable' to be a default opener for file-type 'X'. MIME is important as Android does not use file extensions for app assignment. If I read it right, Intents are key. https://developer.android.com/guide/topics/manifest/manifest-intro