Update to new recipe system (S++ 2.0).

recipes/stb/recipe.py

@@ -1,8 +1,18 @@
 
 from SCons.Script import *
 
-def cook(env: Environment, git_ref: str = "master") -> dict:
-    repo = env.GitBranch(repo_name = 'stb', remote_url = 'https://github.com/nothings/stb.git', git_ref = git_ref)
+_REPO_NAME = 'stb'
+_REPO_URL = 'https://github.com/nothings/stb.git'
+
+
+def versions(env: Environment, update: bool = False):
+    return [(0, 0, 0)]
+
+def dependencies(env: Environment, version) -> 'dict':
+    return {}
+
+def cook(env: Environment, version) -> dict:
+    repo = env.GitBranch(repo_name = _REPO_NAME, remote_url = _REPO_URL, git_ref = 'master')
     checkout_root = repo['checkout_root']
     return {
         'CPPPATH': [checkout_root]