feat: Select start program in developer dialog

In the 'PLC developer', a Python file can now be selected as a start
project on the Revolution Pi. This is transferred to the Revolution
Pi via the new XML-RPC function 'set_plcprogram'. This version is
available from 'revpipyload' 0.11.0.

ui_dev/files.ui

@@ -269,6 +269,26 @@
             </property>
            </spacer>
           </item>
+          <item>
+           <widget class="QPushButton" name="btn_mark_plcprogram">
+            <property name="text">
+             <string/>
+            </property>
+            <property name="icon">
+             <iconset resource="ressources.qrc">
+              <normaloff>:/file/ico/autostart.ico</normaloff>:/file/ico/autostart.ico</iconset>
+            </property>
+            <property name="iconSize">
+             <size>
+              <width>24</width>
+              <height>24</height>
+             </size>
+            </property>
+            <property name="autoDefault">
+             <bool>false</bool>
+            </property>
+           </widget>
+          </item>
          </layout>
         </item>
         <item>