Filtering tracks in library by length should handle abbreviations like lastplayed

[residuum]

Before posting

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• I checked the issue tracker for similar issues
• I checked the changelog if the issue is already resolved
• I tried the latest Clementine build from here

System information

Please provide information about your system and the version of Clementine used.

• Operating System: Debian testing/unstable
• Clementine version: 1.4 rc2

Expected behaviour / actual behaviour

When filtering tracks in the library, it is possible to search for tracks played within a specified time with the syntax lastplayed:<1h30m. It is also possible to filter tracks by length, but not with the abbreviations for minutes, hours, seconds etc. So one must search for nanoseconds now, e.g. length:<60000000000 returns tracks shorter than 1 minute in the library, but length:<1m would be nice for that.

Currently the abbreviations are only filtered in date columns

Clementine/src/library/libraryquery.cpp

Line 110 in 4ab6f35

} else if (Song::kDateColumns.contains(columntoken)) {