CoapClientExcpeiton

- Added new base class for any client-based errors

RequestTimeoutException

- Added new exception type

source/doap/client/exceptions.d

@@ -0,0 +1,44 @@
+module doap.client.exceptions;
+
+import doap.exceptions : CoapException;
+import core.time : Duration;
+
+public class CoapClientException : CoapException
+{
+    this(string msg)
+    {
+        super(msg);
+    }
+}
+
+import doap.client.request : CoapRequestFuture;
+import std.conv : to;
+
+package final class RequestTimeoutException : CoapClientException
+{
+    /** 
+     * The future we timed out on
+     */
+    private CoapRequestFuture future;
+
+    /**
+     * Timeout time
+     */
+    private Duration timeout;
+
+    /** 
+     * Constructs a new timeout exception for
+     * the given future which timed out
+     *
+     * Params:
+     *   future = the future we timed out on
+     *   timeout = the time duration timed out
+     * on
+     */
+    this(CoapRequestFuture future, Duration timeout)
+    {
+        super("Timed out whilst waiting for "~to!(string)(future)~" after "~to!(string)(timeout));
+        this.future = future;
+        this.timeout = timeout;
+    }
+}