Some tags and messages cannot be added to quick filters

[Mikhail Lopatkin]

1. Tag with , symbol in it cannot be edited.
2. Message that looks like /…./ will be interpreted as regex and if the regex is invalid - won’t be added to filters.

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[Mikhail Lopatkin]

Blocked on #153

[Mikhail Lopatkin]

PR #21: Quick filters with escaping

This is a bit ugly solution with regard to regexes: it uses built-in regex quoting if message or tag looks like regex pattern itself.