DSi-based UIs: Add Previous & Next text to language.ini

Author: RocketRobz

romsel_dsimenutheme/nitrofiles/languages/en/language.ini

@@ -130,8 +130,10 @@ B_BACK = \B Back
 Y_DS_MODE_B_BACK = \Y Launch in DS mode  \B Back
 L = \L
 L_PREV = \L Prev Page
+PREV = Previous
 R = \R
 NEXT_R = Next Page \R
+NEXT = Next
 
 SDK_VER = SDK ver: %s
 DS_PHAT_COLORS = DS Phat Colors