snap: Added 'network' interface to be able to read news feed

Also removed 'opengl' interface for the various other tools shipping
with Tiled, since none of them use OpenGL.

snap/snapcraft.yaml

@@ -15,19 +15,19 @@ apps:
   tiled:
     command: desktop-launch ${SNAP}/usr/bin/tiled
     desktop: usr/share/applications/org.mapeditor.Tiled.desktop
-    plugs: [home, opengl, unity7]
+    plugs: [home, opengl, unity7, network]
   tmxviewer:
     command: desktop-launch ${SNAP}/usr/bin/tmxviewer
-    plugs: [home, opengl, unity7]
+    plugs: [home, unity7]
   tmxrasterizer:
     command: desktop-launch ${SNAP}/usr/bin/tmxrasterizer
-    plugs: [home, opengl, unity7]
+    plugs: [home, unity7]
   terraingenerator:
     command: desktop-launch ${SNAP}/usr/bin/terraingenerator
-    plugs: [home, opengl, unity7]
+    plugs: [home, unity7]
   automappingconverter:
     command: desktop-launch ${SNAP}/usr/bin/automappingconverter
-    plugs: [home, opengl, unity7]
+    plugs: [home, unity7]
 
 parts:
   tiled: