Don't flush IO when starting evaluation

Any pending output can remain pending until the buffer fills,
or a later flush occurs.

src/lang/Prolog.java

diff --git a/src/lang/Prolog.java b/src/lang/Prolog.java
index 1e5d7a2..8f97c30 100644
--- a/src/lang/Prolog.java
+++ b/src/lang/Prolog.java
@@ -260,8 +260,6 @@
 	    : 0;
 	previousRuntime = 0;
 
-	userOutput.flush();
-	userError.flush();
 	currentInput  = userInput;
 	currentOutput = userOutput;
     }