ui: improve ui

- Implement PixbufManipulator
- Adapt contactDelegate and historyDelegate and
  smartListDelegate
- Add selection hint to smartList
- Add context menu to smartlist
- Rewrite the IM delegate
- Suppress chat button in favor of selection
- Various value passed to const member to avoid a lot of
  allocation
- Various indent fixes

Change-Id: Id8fdda04e16d8479f99eed060d668e1b0c7f9445
Tuleap: #148
Tuleap: #232
diff --git a/images/ic_arrow_back_white.svg b/images/ic_arrow_back_white.svg
new file mode 100644
index 0000000..367927d
--- /dev/null
+++ b/images/ic_arrow_back_white.svg
@@ -0,0 +1,4 @@
+<svg fill="#FFFFFF" height="48" viewBox="0 0 24 24" width="48" xmlns="http://www.w3.org/2000/svg">
+    <path d="M0 0h24v24H0z" fill="none"/>
+    <path d="M20 11H7.83l5.59-5.59L12 4l-8 8 8 8 1.41-1.41L7.83 13H20v-2z"/>
+</svg>
\ No newline at end of file