Add auto-barter to trade UI and global toggle to trade agreements

caravan.lua

@@ -24,6 +24,7 @@ OVERLAY_WIDGETS = {
     movegoods_hider=movegoods.MoveGoodsHiderOverlay,
     assigntrade=movegoods.AssignTradeOverlay,
     displayitemselector=pedestal.PedestalOverlay,
+    autobarter=trade.AutoBarterOverlay,
 }
 
 INTERESTING_FLAGS = {

docs/caravan.rst

@@ -133,6 +133,13 @@ are trading with. Clicking on the badge will show a list of problematic items,
 and you can click the button on the dialog to deselect all the problematic
 items in your trade list.
 
+**caravan.autobarter**
+
+This overlay provides "Barter (expensive)" and "Barter (cheap)" buttons on the trade
+screen. These buttons automatically select fortress goods to trade that total slightly
+more than the value of the merchant goods you have selected. You can choose whether to
+fill the quota with your most expensive items or your cheapest items.
+
 Trade agreements
 ````````````````
 
@@ -141,8 +148,17 @@ Trade agreements
 This adds a small panel with some useful shortcuts:
 
 * ``Ctrl-a`` for selecting all/none in the currently shown category.
+* ``Shift-a`` for selecting all/none across all item categories globally.
 * ``Ctrl-m`` for selecting items with specific base material price (only
   enabled for item categories where this matters, like gems and leather).
+* ``Ctrl-w`` for selecting items by solid density (weight). This is enabled
+  for categories like boulders, metals, cheese, crafts, and other raw
+  materials where weight matters.
+* ``Ctrl-s`` for saving the current trade agreement requests for the active
+  civilization. Requests are stored per-civ so you can maintain different
+  agreements for different trading partners.
+* ``Ctrl-l`` for loading previously saved trade agreement requests for the
+  active civilization.
 
 Display furniture
 `````````````````