Electron 15, single-instance-lock and setting to disable hardwareMediaKeyHandling (#134)

* Update to Electron 15 and add Flatpak to README (#131)

* Update functional

* Change to 15

* Replace window.hide, window.restart with counterparts

* Fix openexternal by doing default JS

* Change mouse to pointer for <a> elements

* turn mouse to pointer for exit button

* Fix deprecation of Audio for AudioVideo

* Made a small mistake

* Add Flatpak to readme

* 3.0.0 prep

* Added setting to disable multiple tidal-hifi windows (defaults to true)

fixes #121

* Added setting to disable HardwareMediaKeyHandling (defaults to false)

fixes #133

Co-authored-by: Marie <marie@kaifa.ch>

README.md

@@ -15,6 +15,7 @@ The web version of [listen.tidal.com](https://listen.tidal.com) running in elect
   - [Using releases](#using-releases)
     - [Snap install](#snap-install)
   - [Arch Linux](#arch-linux)
+  - [Flatpak](#flatpak)
   - [Using source](#using-source)
 - [features](#features)
 - [Integrations](#integrations)
@@ -61,6 +62,14 @@ Arch Linux users can use the AUR to install tidal-hifi:
 trizen tidal-hifi-bin
 ```
 
+### Flatpak
+
+To install via Flatpak run the following command:
+
+```sh
+flatpak install flathub com.mastermindzh.tidal-hifi
+```
+
 ### Using source
 
 To install and work with the code on this project follow these steps: