[feat] SDL2: add window icon (new logo) (#3884)

Also update Ubuntu Touch icon

Fixes #2000, fixes #3858

Makefile

@@ -302,7 +302,7 @@ appimageupdate: all
 	ln -sf ../../$(APPIMAGE_DIR)/AppRun $(INSTALL_DIR)/koreader
 	ln -sf ../../$(APPIMAGE_DIR)/koreader.appdata.xml $(INSTALL_DIR)/koreader
 	ln -sf ../../$(APPIMAGE_DIR)/koreader.desktop $(INSTALL_DIR)/koreader
-	ln -sf ../../$(UBUNTUTOUCH_DIR)/koreader.png $(INSTALL_DIR)/koreader
+	ln -sf ../../resources/koreader.png $(INSTALL_DIR)/koreader
 	# TODO at best this is DebUbuntu specific
 	ln -sf /usr/lib/x86_64-linux-gnu/libSDL2.so $(INSTALL_DIR)/koreader/libs
 ifeq ("$(wildcard $(APPIMAGETOOL))","")

frontend/device/sdl/device.lua

@@ -38,6 +38,9 @@ function Device:init()
         self.hasClipboard = yes
         self.screen = require("ffi/framebuffer_SDL2_0"):new{device = self, debug = logger.dbg}
 
+        local ok, re = pcall(self.screen.setWindowIcon, self.screen, "resources/koreader.png")
+        if not ok then logger.warn(re) end
+
         local input = require("ffi/input")
         self.input = require("device/input"):new{
             device = self,