general: Iv* to Lp*

We're probably going to be keeping `loupe` as the codename
and binary name going forward.

data/gtk/image_view.ui

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <interface>
-  <template class="IvImageView" parent="AdwBin">
+  <template class="LpImageView" parent="AdwBin">
     <property name="css-name">imageview</property>
     <property name="focusable">True</property>
     <property name="focus-on-click">True</property>
@@ -8,7 +8,7 @@
       <object class="GtkOverlay">
         <property name="hexpand">True</property>
         <child>
-          <object class="IvImage" id="picture">
+          <object class="LpImage" id="picture">
             <property name="halign">center</property>
             <property name="valign">center</property>
           </object>

data/gtk/window.ui

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <interface>
-  <template class="IvWindow" parent="AdwApplicationWindow">
+  <template class="LpWindow" parent="AdwApplicationWindow">
     <property name="default-width">600</property>
     <property name="default-height">498</property>
     <property name="width-request">360</property>
@@ -15,7 +15,7 @@
         <property name="modal">false</property>
         <property name="flap">
           <object class="GtkHeaderBar" id="headerbar">
-            <property name="show_title_buttons" bind-source="IvWindow" bind-property="fullscreened" bind-flags="sync-create|invert-boolean"/>
+            <property name="show_title_buttons" bind-source="LpWindow" bind-property="fullscreened" bind-flags="sync-create|invert-boolean"/>
             <binding name="opacity">
               <lookup type="GtkWidget" name="opacity">
                 <lookup name="controls">image_view</lookup>
@@ -51,7 +51,7 @@
               </object>
             </child>
             <child>
-              <object class="IvImageView" id="image_view"/>
+              <object class="LpImageView" id="image_view"/>
             </child>
           </object>
         </property>