enable GTK theme as default and set it to Arc-Darker. Set featherpad as default application for text/plain and shellscript

Summary: Enable GTK theme as default and set it to Arc-Darker. Set featherpad as default application for text/plain and shellscript

Test Plan: check in lxqt-config-appearance for GTK theme. Opena text/plain file

Reviewers: tsimonq2, wxl

Reviewed By: tsimonq2, wxl

Differential Revision: https://phab.lubuntu.me/D22

debian/changelog

@@ -1,3 +1,11 @@
+lubuntu-default-settings (1.15) cosmic; urgency=medium
+
+  * Enable GTK theme as default.
+  * Set GTK theme to Arc-Darker.
+  * Set featherpad as default application for text/plain and shellscript.* 
+
+ -- Hans P. Möller <hmoller@gmail.com>  Sat, 29 Sep 2018 23:24:06 -0300
+
 lubuntu-default-settings (1.14) cosmic; urgency=medium
 
   [ Wendy Hill ]

src/etc/xdg/xdg-Lubuntu/lxqt/lxqt-config-appearance.conf

@@ -0,0 +1,2 @@
+[General]
+ControlGTKThemeEnabled=true

src/etc/xdg/xdg-Lubuntu/mimeapps.list

@@ -0,0 +1,3 @@
+[Default Applications]
+text/plain=featherpad.desktop;
+application/x-shellscript=featherpad.desktop;

src/usr/share/glib-2.0/schemas/50_lubuntu.gschema.override

@@ -0,0 +1,2 @@
+[org.gnome.desktop.interface]
+gtk-theme='Arc-Darker'