Zipfile search issues

These are some remaining issues from the zipfile search patch. Trying to collect the issues here and hope to take care of them.

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Sidebar Filters

• File Type Filter doesn't filter zip contents (documents in zip files won't show if Documents selected)
• Modified Filter only filters zip file, not contents
• Other Filter - Doesn't allow you to expand zip contents if .zip is searched (not sure if it should change)
• Other Filter - Doesn't filter zip contents by ext (if .txt searched it won't show .txt files in zip files)

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Fulltext Search

• Doesn't filter files through def is_txt (to filter non-text files)
• Doesn't filter files through def check_charset (which checks for non-utf-8 files and skips binary files)
• Doesn't search zip documents within zip files (Example, .odt file in .zip file will not be searched).

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Filename Search

• Match Results Exactly hides zip files (workaround, select 'Match Exactly' then search)
• Doesn't search zip files within zip files for filenames.

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Miscellaneous

• Right Click -> Open on folder in .zip file gives an error (!39 (merged))
• Freeze with special files (like pipe files). Zipfile doesn't check if os.path.isfile, needs to be done before checking if zip. (!36 (merged))
• Copy Location probably shouldn't show on zipped files since they don't have a location. Currently the path of the archive itself is copied, which could be confusing.

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