Add a class that keeps track of the implementation information.

src/main/java/org/nwapw/abacus/plugin/NumberImplementation.java

@@ -0,0 +1,17 @@
+package org.nwapw.abacus.plugin;
+
+import org.nwapw.abacus.number.NumberInterface;
+
+import java.util.Map;
+import java.util.function.Function;
+
+public abstract class NumberImplementation {
+
+    private Class<? extends NumberInterface> implementation;
+    private Map<String, Function<NumberInterface, NumberInterface>> promotionPaths;
+    private int priority;
+
+    public abstract NumberInterface instanceForString(String string);
+    public abstract NumberInterface instanceForPi();
+
+}