Initial support for sync

Only sends the sync, does not do anything with the response yet.
Handling the response will be implemented in the next several commits,
piece by piece.

FossilOrigin-Name: 17e299f073f39e55dfe0b8a4bd1b34c8529400138d147df5a7229336df6ba04f

src/exceptions/MTXSyncFailedException.h

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2020, Jonathan Schleifer <js@nil.im>
+ *
+ * https://fossil.nil.im/objmatrix
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice is present in all copies.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#import <ObjFW/ObjFW.h>
+
+#import "MTXClientException.h"
+
+OF_ASSUME_NONNULL_BEGIN
+
+@interface MTXSyncFailedException: MTXClientException
+@end
+
+OF_ASSUME_NONNULL_END