Modern Bulk Rail Loaders: Pooled

A pooled-inventory rework of the bulk rail loader concept. Every station has
one hidden cargo inventory (the pool); each visible silo is a Factorio 2.0
proxy-container — a physical window onto that shared pool. Because there is
only one inventory per station:

• Contents can never get unbalanced between wagons. A train's order completes
  whenever the station total suffices — no stuck partial loads.
• There is no balancing logic and no recurring UPS cost for it.
• Factory inserters/loaders can feed or drain any silo; it all lands in the
  same pool.

Requires Factorio ≥ 2.0.38 (the version that introduced proxy containers).

Usage

1. Open a train stop and use the Bulk loaders panel: pick the wagon count,
   locomotive gap, and the station mode (Load / Unload).
2. Silos are placed automatically over each wagon slot; blocked positions get
   ghosts you can revive after clearing obstructions.
3. Loading stations show a hopper structure over each wagon; unloading
   stations show a tipper grate beneath the track.

Circuit network / Cybersyn

Wire exactly one silo (any of them) to your circuit network or Cybersyn
combinator — every silo reports the full shared pool, so wiring two silos
doubles the reading.

Design notes

• The pool is a hidden, indestructible container placed at the train stop. Its
  usable size is silo capacity × silo count, enforced with an inventory bar.
• Mining a silo loses nothing (items live in the pool). Removing the last
  silo of a station spills the pool contents on the ground rather than voiding
  them.
• Stations are uniform: the whole station either loads or unloads. Mixed
  stations would mix incoming and outgoing cargo in one pool.
• Hand-placed silos attach to the nearest train stop within 100 tiles
  (preferring stops that already have silos), or get a private pool if none.

Licensing / attribution

• Code: original to this mod.
• All graphics (graphics/loader-*.png, graphics/unloader-*.png) are from
  railloader by mspielberg (therax),
  licensed LGPL-3.0 (see LICENSE-railloader-graphics). Keep that license
  file and this attribution if you redistribute the mod.

Development

Symlink into your mods folder under the mod's name (the folder name must match
info.json):

ln -s /path/to/this/repo ~/.factorio/mods/modern-bulk-rail-loader-pooled