added preliminary API for custom literals from Java. Not functional yet

src/runtime/java/org/grammaticalframework/pgf/Concr.java

@@ -38,6 +38,8 @@ public class Concr {
 
 	public native void unload();
 
+	public native void addLiteral(String cat, LiteralCallback callback);
+
 	//////////////////////////////////////////////////////////////////
 	// private stuff
 	

src/runtime/java/org/grammaticalframework/pgf/ExprBuilder.java

@@ -0,0 +1,16 @@
+package org.grammaticalframework.pgf;
+
+public class ExprBuilder {
+	public ExprBuilder() {
+		
+	}
+
+	ExprBuilder(long poolRef) {
+	}
+
+	public native Expr mkApp(String fun, Expr... args);
+
+	public native Expr mkLiteral(String s);
+	public native Expr mkLiteral(int n);
+	public native Expr mkLiteral(double d);
+}

src/runtime/java/org/grammaticalframework/pgf/LiteralCallback.java

@@ -0,0 +1,5 @@
+package org.grammaticalframework.pgf;
+
+public interface LiteralCallback {
+	public int match(Concr concr, int lin_idx, ExprBuilder builder, String sentence, int start_offset);
+}

src/runtime/java/org/grammaticalframework/pgf/NercLiteralCallback.java

@@ -0,0 +1,7 @@
+package org.grammaticalframework.pgf;
+
+public class NercLiteralCallback implements LiteralCallback {
+	public int match(Concr concr, int lin_idx, ExprBuilder builder, String sentence, int start_offset) {
+		return start_offset;
+	}
+}