ui: Move .ui-files to src/

Closes #46

po/POTFILES.in

@@ -1,8 +1,3 @@
-data/gtk/image_page.ui
-data/gtk/image_view.ui
-data/gtk/print.ui
-data/gtk/properties_view.ui
-data/gtk/window.ui
 data/org.gnome.Loupe.desktop.in.in
 data/org.gnome.Loupe.metainfo.xml.in.in
 data/resources/gtk/help-overlay.ui
@@ -23,10 +18,15 @@ src/util/mod.rs
 src/widgets/drag_overlay.rs
 src/widgets/image.rs
 src/widgets/image_page.rs
+src/widgets/image_page.ui
 src/widgets/image_view.rs
+src/widgets/image_view.ui
 src/widgets/mod.rs
 src/widgets/print.rs
+src/widgets/print.ui
 src/widgets/print_preview.rs
 src/widgets/properties_view.rs
+src/widgets/properties_view.ui
 src/widgets/sliding_view.rs
 src/window.rs
+src/window.ui

src/widgets/image_page.rs

@@ -33,7 +33,7 @@ mod imp {
     use super::*;
 
     #[derive(Debug, Default, CompositeTemplate)]
-    #[template(file = "../../data/gtk/image_page.ui")]
+    #[template(file = "image_page.ui")]
     pub struct LpImagePage {
         #[template_child]
         pub(super) stack: TemplateChild<gtk::Stack>,

src/widgets/image_view.rs

@@ -58,7 +58,7 @@ mod imp {
     use super::*;
 
     #[derive(Debug, Default, CompositeTemplate)]
-    #[template(file = "../../data/gtk/image_view.ui")]
+    #[template(file = "image_view.ui")]
     pub struct LpImageView {
         /// Direct child of this Adw::Bin
         #[template_child]

src/widgets/print.rs

@@ -211,7 +211,7 @@ mod imp {
     use super::*;
 
     #[derive(Debug, Default, CompositeTemplate, Properties)]
-    #[template(file = "../../data/gtk/print.ui")]
+    #[template(file = "print.ui")]
     #[properties(wrapper_type = super::LpPrint)]
     pub struct LpPrint {
         #[template_child]

src/widgets/properties_view.rs

@@ -38,7 +38,7 @@ mod imp {
     use super::*;
 
     #[derive(Debug, Default, CompositeTemplate)]
-    #[template(file = "../../data/gtk/properties_view.ui")]
+    #[template(file = "properties_view.ui")]
     pub struct LpPropertiesView {
         pub(super) file: RefCell<Option<glib::WeakRef<gio::File>>>,
         pub(super) image: RefCell<Option<glib::WeakRef<LpImage>>>,

src/window.rs

@@ -66,7 +66,7 @@ mod imp {
     // we'd need to have a `new()` function in the
     // `impl ObjectSubclass for $TYPE` section.
     #[derive(Default, Debug, CompositeTemplate)]
-    #[template(file = "../data/gtk/window.ui")]
+    #[template(file = "window.ui")]
     pub struct LpWindow {
         // Template children are used with the
         // TemplateChild<T> wrapper, where T is the