Log Message:
Update onscripter to 20140504.

Upstream changes (no English changelog):

20140504:
 - fix a bug that can't read in label information in some particular cases
 - fix warnings by gcc-4.7.2

20140422 (serious bug fix):
 - fix a bug slippled in 20140406 that prevents save from mouse
   right click menu

20140406:
 - fix incorrect movie URLs on Android version
 - fix a bug in savegame insns that handles a 32 bit integer
   for save data differently from the original nscripter
 - improve bgm and mp3loop insns to support
   "(time from the start of bgm)filename" format for loop bgm
 - fix a bug in skip insn that causes infinite loop when 0 is passed
 - implement menu_clock_def and menu_click_page insns
 - fix a bug in textgosub insn that doesn't return to the labeled insn
   specfied by "return *label" format