Move resource files to resources/ directory

This is to make them more managable

src/resources/ui/astrognome.ui

@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+    <requires lib="gtk+" version="3.0" />
+    <menu id="app-menu">
+        <section>
+            <item>
+                <attribute name="label" translatable="yes">New window</attribute>
+                <attribute name="action">app.new-window</attribute>
+                <attribute name="accel">&lt;Primary&gt;n</attribute>
+            </item>
+            <item>
+                <attribute name="label" translatable="yes">Open</attribute>
+                <attribute name="action">app.open</attribute>
+                <attribute name="accel">&lt;Primary&gt;o</attribute>
+            </item>
+        </section>
+        <section>
+            <item>
+                <attribute name="label" translatable="yes">Preferences</attribute>
+                <attribute name="action">app.preferences</attribute>
+                <attribute name="accel">&lt;Primary&gt;p</attribute>
+            </item>
+        </section>
+        <section>
+            <item>
+                <attribute name="label" translatable="yes">About Astrognome</attribute>
+                <attribute name="action">app.about</attribute>
+            </item>
+            <item>
+                <attribute name="label" translatable="yes">Quit</attribute>
+                <attribute name="action">app.quit</attribute>
+                <attribute name="accel">&lt;Primary&gt;q</attribute>
+            </item>
+        </section>
+    </menu>
+</interface>