refactor image resource loading code in minui

Reduce the number of copies of libpng boilerplate.  Rename
res_create_* functions to be more clear.  Make explicit the use of the
framebuffer pixel format for images, and handle more combinations of
input and output (eg, loading a grayscale image for display rather
than use as a text alpha channel).

Change-Id: I3d41c800a8f4c22b2f0167967ce6ee4d6b2b8846
diff --git a/recovery.cpp b/recovery.cpp
index 448f315..e956ed7 100644
--- a/recovery.cpp
+++ b/recovery.cpp
@@ -974,8 +974,8 @@
     ui = device->GetUI();
     gCurrentUI = ui;
 
-    ui->Init();
     ui->SetLocale(locale);
+    ui->Init();
     ui->SetBackground(RecoveryUI::NONE);
     if (show_text) ui->ShowText(true);