sync experimental with trunk

source/libs/lua52/lua-5.2.3/src/lstring.c

source/libs/luajit/LuaJIT-2.0.2/src/lj_str.c

source/texk/web2c/lib/texmfmp.c

source/texk/web2c/luatexdir/font/luafont.w

source/texk/web2c/luatexdir/font/mapfile.w

source/texk/web2c/luatexdir/font/pkin.w

source/texk/web2c/luatexdir/font/sfnt.h

source/texk/web2c/luatexdir/font/subfont.w

source/texk/web2c/luatexdir/font/texfont.w

source/texk/web2c/luatexdir/font/tounicode.w

source/texk/web2c/luatexdir/font/vfovf.w

source/texk/web2c/luatexdir/font/writecff.w

source/texk/web2c/luatexdir/font/writefont.w

source/texk/web2c/luatexdir/font/writet1.w

source/texk/web2c/luatexdir/font/writet3.w

source/texk/web2c/luatexdir/font/writettf.w

source/texk/web2c/luatexdir/font/writetype0.w

source/texk/web2c/luatexdir/font/writetype2.w

source/texk/web2c/luatexdir/image/image.h

source/texk/web2c/luatexdir/image/pdftoepdf.w