Citro2d switch (#175)

* Switch from pp2d to citro2d

* Fix various bugs by updating libarchive

* Begin work on translation infrastructure

* Switch to libpng for various improvements

* Fixed race condition in icon scrolling

* Use spritesheets to load sprites marginally faster and use less memory

* Various Readme fixes

* Huge improvements to QR reader speed and screen tearing

* Don't try to preview themes/splashes when there are none

* Prevent playing audio when ndspInit() fails

* Don't wait for audio to load before displaying preview

* Fix bug when shuffle themes didn't have BGM

* Fix bug caused by files not being zeroed out when created

assets/sprites.t3s

@@ -0,0 +1,23 @@
+--atlas -f rgba8888 -z auto
+arrow_up.png
+arrow_down.png
+arrow_left.png
+arrow_right.png
+battery0.png
+battery1.png
+battery2.png
+battery3.png
+battery4.png
+battery5.png
+browse.png
+charging.png
+download.png
+exit.png
+installed.png
+list.png
+preview.png
+select.png
+shuffle.png
+shuffle_no_bgm.png
+sort.png
+start.png