I fix ISO No in String class in comparison with ISO_IEC_30170_2012(E)-Charactor_PDF_document.pdf
Merge pull request #1458 from suzukaze/fix-iso-no-in-string-class

I fix ISO no in String class in comparison with ISO_IEC_30170_2012(E)
fix #1459

gen_vmassignment() missed a pop() in a conditional branch, but we have
to keep each conditional branch 's stack depth the same all the time
when it left execution.
Merge pull request #1460 from Fleurer/fix-1459

fix #1459
Merge branch 'master' into iij

Conflicts:
	test/t/string.rb