Introduced recipe repositories.

addons/recipe_repository.py

@@ -0,0 +1,11 @@
+
+
+import os
+
+Import('env')
+def _recipe_repository(env, repo_name: str, remote_url: str, git_ref: str = 'master') -> None:
+    repo = env.GitBranch(repo_name = repo_name, remote_url = remote_url, git_ref = git_ref)
+    env.Append(SPP_RECIPES_FOLDERS = [os.path.join(repo['checkout_root'], 'recipes')])
+
+env.AddMethod(_recipe_repository, 'RecipeRepo')
+Return('env')