writing files

[Warpten]

Problems to expect:

• Heuristics for section assignment of each member:
  1. Bitpacking (bit counting if column.max_value < (column.type.max_value >> 8)
  2. Choosing between pallet and common (default value heuristic?)
• Maintain a string pool - whenever an item is added to the container, we need to extract strings from it
• Subsidiary: when is a string pool not needed?