Clean repo for open source release

Remove build artifacts, dev tool configs, unused dependencies,
and third-party source dumps. Add proper README, update .gitignore,
clean up Makefile.

src/main/java/com/tiedup/remake/state/ISaleable.java

@@ -0,0 +1,39 @@
+package com.tiedup.remake.state;
+
+import com.tiedup.remake.util.tasks.ItemTask;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * Standalone sale state interface for entities that can be put up for sale.
+ *
+ * @see IRestrainable
+ */
+public interface ISaleable {
+
+    /**
+     * Check if this entity is marked for sale by a captor.
+     *
+     * @return true if captive is being sold
+     */
+    boolean isForSell();
+
+    /**
+     * Get the sale price for this captive.
+     *
+     * @return The sale price ItemTask, or null if not for sale
+     */
+    @Nullable
+    ItemTask getSalePrice();
+
+    /**
+     * Mark this captive as for sale with the given price.
+     *
+     * @param price The sale price
+     */
+    void putForSale(ItemTask price);
+
+    /**
+     * Cancel the sale and reset sale state.
+     */
+    void cancelSale();
+}