Update tutorial

Two main changes:
 - "Seek nearby targets" is no longer enabled by default.
 - The application asks the user to save new projects immediately.

Various minor edits were also made.

A couple of the images are slightly stale, showing ".org" rather than
".addrs", but they're in the advanced section and the difference
isn't notable.

SourceGen/DisasmProject.cs

@@ -2111,7 +2111,6 @@ namespace SourceGen {
         /// <summary>
         /// Returns the next redo operation, and moves the pointer to the next item.
         /// </summary>
-        /// <returns></returns>
         public ChangeSet PopRedoSet() {
             if (!CanRedo) {
                 throw new Exception("Can't redo");