Implement reading/writing entity status and expose feature bit

Hi, I just needed to mark and save features in a mesh and hacked in the essentials for that.

I hope this is useful as-is, but I'd be happy to make changes/improvements.

added 22 commits

• d4a5c6f5...ed217314 - 21 commits from branch master
• 403d3afa - Merge branch 'master' into feature/status-and-features

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added 1 commit

• a2ad83c3 - Typo

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merged

mentioned in commit 7e82ad6b