Improved error handling

* Created AsyncTaskService to build async UI operations which always log
uncaught exceptions
* Changed all executor service invocations in the UI to invocations of
AsyncTaskService
* Improved error handling in some other places, especially
try-with-resources
* Unlocking read/write locks in NioFile when opening of a channel fails

main/commons/src/main/java/org/cryptomator/common/ConsumerThrowingException.java

@@ -1,7 +1,7 @@
 package org.cryptomator.common;
 
 @FunctionalInterface
-public interface ConsumerThrowingException<T, E extends Exception> {
+public interface ConsumerThrowingException<T, E extends Throwable> {
 
 	void accept(T t) throws E;
 

main/commons/src/main/java/org/cryptomator/common/RunnableThrowingException.java

@@ -1,7 +1,7 @@
 package org.cryptomator.common;
 
 @FunctionalInterface
-public interface RunnableThrowingException<T extends Exception> {
+public interface RunnableThrowingException<T extends Throwable> {
 
 	void run() throws T;
 

main/commons/src/main/java/org/cryptomator/common/StackTrace.java

@@ -0,0 +1,56 @@
+/*******************************************************************************
+ * Copyright (c) 2016 Markus Kreusch and others.
+ * This file is licensed under the terms of the MIT license.
+ * See the LICENSE.txt file for more info.
+ *
+ * Contributors:
+ *     Markus Kreusch - initial implementation
+ *******************************************************************************/
+package org.cryptomator.common;
+
+import java.util.stream.Stream;
+
+/**
+ * Utility to print stack traces while analyzing issues.
+ * 
+ * @author Markus Kreusch
+ */
+public class StackTrace {
+
+	public static void print(String message) {
+		Thread thread = Thread.currentThread();
+		System.err.println(stackTraceFor(message, thread));
+	}
+
+	private static String stackTraceFor(String message, Thread thread) {
+		StringBuilder result = new StringBuilder();
+		appendMessageAndThreadName(result, message, thread);
+		appendStackTrace(thread, result);
+		return result.toString();
+	}
+
+	private static void appendStackTrace(Thread thread, StringBuilder result) {
+		Stream.of(thread.getStackTrace()) //
+				.skip(4) //
+				.forEach(stackTraceElement -> append(stackTraceElement, result));
+	}
+
+	private static void appendMessageAndThreadName(StringBuilder result, String message, Thread thread) {
+		result //
+				.append('[') //
+				.append(thread.getName()) //
+				.append("] ") //
+				.append(message);
+	}
+
+	private static void append(StackTraceElement stackTraceElement, StringBuilder result) {
+		String className = stackTraceElement.getClassName();
+		String methodName = stackTraceElement.getMethodName();
+		String fileName = stackTraceElement.getFileName();
+		int lineNumber = stackTraceElement.getLineNumber();
+		result.append('\n') //
+				.append(className).append(':').append(methodName) //
+				.append(" (").append(fileName).append(':').append(lineNumber).append(')');
+	}
+
+}

main/commons/src/main/java/org/cryptomator/common/SupplierThrowingException.java

@@ -0,0 +1,8 @@
+package org.cryptomator.common;
+
+@FunctionalInterface
+public interface SupplierThrowingException<T, E extends Throwable> {
+
+	T get() throws E;
+
+}