Items name and description

[Tavren]

Add name and description for items Probably rename file what holding items or make separate files for each item class

• [x] ConveyorCrateItem
• [x] ConveyorItem
• [x] ConveyorVerticalItem
• [x] ConveyorVerticalEndItem
• [x] ConveyorImporterItem
• [x] ConveyorExporterItem