Plugin 2048: optimize small tiles

Change 12x12 and 22x22 sized tiles to hand-optimized ones
with better readibility :)
Tile values >= 1024 are abbreviated to "1k", "2k" etc.

Change-Id: I15f4649b20442b71027a3b1564bc51c7e72105ce

manual/plugins/2048.tex

@@ -5,6 +5,10 @@
 
 The game is won when a tile with a value of 2048 is created, and the player loses when there are no more possible moves.
 
+\note{On players with a small screen tiles with a value greater than 1000 are shortened
+to ``1k'', ``2k'' and so forth (\emph{k} is the abbreviation of \emph{kilo},
+which -- in computer talk -- means a multiple of 1024).}
+
 \begin{btnmap}
   \PluginUp, \PluginDown, \PluginLeft, \PluginRight
   \opt{HAVEREMOTEKEYMAP}{& \PluginRCUp, \PluginRCDown, \PluginRCLeft, \PluginRCRight}