Add allowsReading and allowsWriting methods

base/src/main/kotlin/de/staropensource/engine/base/implementable/stream/Stream.kt

@@ -700,7 +700,33 @@ abstract class Stream(
          *
          * @since v1-alpha10
          */
-        READ_WRITE,
+        READ_WRITE;
+
+        /**
+         * Returns whether this mode
+         * allows stream reading.
+         *
+         * @return allows reading?
+         * @since v1-alpha10
+         */
+        fun allowsReading(): Boolean = when(this) {
+            READ -> true
+            WRITE -> false
+            READ_WRITE -> true
+        }
+
+        /**
+         * Returns whether this mode
+         * allows stream reading.
+         *
+         * @return allows reading?
+         * @since v1-alpha10
+         */
+        fun allowsWriting(): Boolean = when(this) {
+            READ -> false
+            WRITE -> true
+            READ_WRITE -> true
+        }
     }
 
     /**