Log Message:
Update onscripter to 20130223.

Upstream changes summary (only Japanese log available)

20130223
 - fix bug of game insn that resets loaded default cursor
 - fix bug that backlog doesn't show all text due to buffer overflow
   in some case

20130216
 - implement luacall reset
 - fix bug in definereset insn that resets global variables even during
   globalon insn is active
 - make definereset insn load system.lua
 - handle >255 values for sprite transparent value

20130203
 - fix iOS SDK bug

20130202
 - implement checkkey insn
 - implement NL_dofile, NSGetSkip, NSGetWindowSize, NSTimer, NSGetKey,
   NSUpdate, NSSpClear, NSSpGetInfo, NSSpGetPos, NSSpLoad, NSSpMove,
   and NSSpVisible insns for NSLua
 - update Android SDK