Fixed thread safety for Terminal implementations. Changed Terminal implementation on windows to Flush System.out/System.err

src/main/java/net/rubygrapefruit/platform/ThreadSafe.java

@@ -0,0 +1,7 @@
+package net.rubygrapefruit.platform;
+
+/**
+ * Indicates that the given class or method is thread safe.
+ */
+public @interface ThreadSafe {
+}