snapshot-357

• Add beforesimdraw and aftersimdraw events
• Sample properties when shift is held
• Implement stamp renaming
• Clear stamp browser selection when page contents change
• Fix header return value from HTTPRequest:finish, now returns both name and value again
• Fix http.post using wrong argument as POST data
• sim.loadStamp: default includePressure to 1
• Fix "does not exist" showing up when loading stamps by id or filepath in console
• Add includePressure to saveStamp as well
• Add stack trace to bluescreen on some systems
• Add platform clipboard option to settings
• Fix requests not being marked done when they fail early