Detect unclosed literals

[n-isaka]

• "で閉じられていない文字リテラルがある場合、コンパイルが無限ループする問題を修正した

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• Fixed an issue where compilation would not complete if there were unclosed literals

[GitMensch]

Please include new testsuite entries for bugs you fix - this ensures that they don't resurrect... and gives me some additional tests I can add to GnuCOBOL if missing as well :-)

Also: for me, most of the changes should really have changelog entries...