Removed SharedFileChannel transferTo and corresponding methods

* Removed from SharedFileChannel and Test
* Refactored Copier#copy(File,File) to sequence of truncated, followed
by looping read and write till EOF
* Changed tests accordingly
* Implemented CryptoWritableFile#truncate to make things work

main/commons-test/src/main/java/org/cryptomator/common/test/mockito/Answers.java

@@ -0,0 +1,61 @@
+package org.cryptomator.common.test.mockito;
+
+import static java.util.Arrays.asList;
+
+import java.util.function.Consumer;
+
+import org.mockito.invocation.InvocationOnMock;
+import org.mockito.stubbing.Answer;
+
+public class Answers {
+
+	public static <T> Answer<T> collectParameters(Answer<T> answer, Consumer<?>... parameterConsumers) {
+		return new Answer<T>() {
+			@SuppressWarnings({"rawtypes", "unchecked"})
+			@Override
+			public T answer(InvocationOnMock invocation) throws Throwable {
+				for (int i = 0; i < invocation.getArguments().length; i++) {
+					if (parameterConsumers.length > i) {
+						((Consumer) parameterConsumers[i]).accept(invocation.getArguments()[i]);
+					}
+				}
+				return answer.answer(invocation);
+			}
+		};
+
+	}
+
+	@SafeVarargs
+	public static <T> Answer<T> consecutiveAnswers(Answer<T>... answers) {
+		if (answers == null || answers.length == 0) {
+			throw new IllegalArgumentException("Required at least one answer");
+		}
+		if (asList(answers).contains(null)) {
+			throw new IllegalArgumentException("No answers must be null");
+		}
+		return new Answer<T>() {
+			private int nextIndex = 0;
+
+			@Override
+			public T answer(InvocationOnMock invocation) throws Throwable {
+				try {
+					return answers[nextIndex].answer(invocation);
+				} finally {
+					nextIndex = (nextIndex + 1) % answers.length;
+				}
+			}
+
+		};
+	}
+
+	public static <T> Answer<T> value(T value) {
+		return new Answer<T>() {
+			@Override
+			public T answer(InvocationOnMock invocation) throws Throwable {
+				return value;
+			}
+
+		};
+	}
+
+}