PR into master from dev/olga/9295-Incorrect-rendering-for-textit-v1

[OlgaRedozubova]

branch: dev/olga/9295-Incorrect-rendering-for-textit-v1

Fixed issues:

• [mmd] Incorrect rendering for [\textit{} #9295
• [snip web] Copy dialog won't go away #9300
• Brace matching error in caption #317

1. Incorrect rendering for [\textit{}

Using [ before some inline rules caused duplicate rendering. Fix: All inline rules should use silent to prevent this rule from being applied if the rule is called for validation

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After:

2. Copy dialog won't go away

Added escapeHtml for clipboardCopyElement

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3. Brace matching error in caption

Changed the closing bracket search rule for \caption{...}

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