DefaultScriptInterpreter: fix newline accumulation

From @skalarproduktraum: "Before when walking the history,
a trailing \n got appended to the submitted command.
Unfortunately, these accumulated over time."

Fixes scijava/scijava-ui-swing#21.

Author: ctrueden

src/main/java/org/scijava/script/DefaultScriptInterpreter.java

@@ -186,22 +186,23 @@ public Object interpret(final String line) throws ScriptException {
 			if (!shouldEvaluatePendingInput(true)) return MORE_INPUT_PENDING;
 		}
 
+		if (pendingLineCount > 0) buffer.append("\n");
 		pendingLineCount++;
 		buffer.append(line);
-		buffer.append("\n");
+		final String command = buffer.toString();
 
 		if (!(engine instanceof Compilable)) {
 			// Not a compilable language.
 			// Evaluate directly, with no multi-line statements possible.
 			try {
-				return eval(buffer.toString());
+				return eval(command);
 			}
 			finally {
 				reset();
 			}
 		}
 
-		final CompiledScript cs = tryCompiling(buffer.toString(),
+		final CompiledScript cs = tryCompiling(command, //
 			getPendingLineCount(), line.length());
 
 		if (cs == null) {
@@ -215,7 +216,7 @@ public Object interpret(final String line) throws ScriptException {
 		}
 		// Command is complete; evaluate the compiled script.
 		try {
-			addToHistory(buffer.toString());
+			addToHistory(command);
 			return cs.eval();
 		}
 		finally {