Font Validator: Fix loading mkv subtitles and fonts in some cases#15

Funami580 wants to merge 1 commit intoTypesettingTools:masterTypesettingTools/Myaamori-Aegisub-Scripts:masterfrom

Funami580:fix_mkv_mimetype_comparisonFunami580/Myaamori-Aegisub-Scripts:fix_mkv_mimetype_comparisonCopy head branch name to clipboard