Add sketch folder to include directories

Because everything is built in another directory than the sketch folder, it is impossible to share common code between sketches or other C++ projects when all of them are in the same repository. Even with the library for Arduino, it would be strange to use one in another C++ project. This commit aims to make the share possible by adding the possibility to specify relative include paths to the sketch file.

Author: mihaizh

container_find_includes.go

@@ -135,6 +135,9 @@ func (s *ContainerFindIncludes) Run(ctx *types.Context) error {
 	}
 
 	sketch := ctx.Sketch
+	// Add the folder containing the sketch to the include directories
+	appendIncludeFolder(ctx, cache, "", "", filepath.Dir(sketch.MainFile.Name))
+	
 	mergedfile, err := types.MakeSourceFile(ctx, sketch, filepath.Base(sketch.MainFile.Name)+".cpp")
 	if err != nil {
 		return i18n.WrapError(err)