Fixed autocompletion for eclipse project.

By adding build project as a reference project.

.project

@@ -3,6 +3,7 @@
 	<name>ArduPilotMega-Source@ardupilotone</name>
 	<comment></comment>
 	<projects>
+		<project>ArduPilotMega@ardupilotone-unix</project>
 	</projects>
 	<buildSpec>
 	</buildSpec>

README.txt

@@ -58,6 +58,10 @@ Building using eclipse
             properly. Source and header files for most languages are under the Text tree. 
             Add "*.pde" as a C++ Source.
 
+	Autocompletion:
+	
+		Right click on source project -> Properties -> Project References -> apm-build Project
+    
     Advanced:
     
         * Regenerating the eclipse source project file: