Revert "all constructor arguments optional, maintain backward compatibility"

This reverts commit afc6158385.

mastodon/Mastodon.py

@@ -174,7 +174,7 @@ class Mastodon:
     ###
     # Authentication, including constructor
     ###
-    def __init__(self, access_token=None, client_id=None, client_secret=None,
+    def __init__(self, client_id, client_secret=None, access_token=None,
                  api_base_url=__DEFAULT_BASE_URL, debug_requests=False,
                  ratelimit_method="wait", ratelimit_pacefactor=1.1,
                  request_timeout=__DEFAULT_TIMEOUT, mastodon_version=None,
@@ -248,11 +248,14 @@ class Mastodon:
             raise MastodonIllegalArgumentError("Invalid ratelimit method.")
         
         # Token loading
-        if self.access_token is None:
         if os.path.isfile(self.client_id):
             with open(self.client_id, 'r') as secret_file:
                 self.client_id = secret_file.readline().rstrip()
                 self.client_secret = secret_file.readline().rstrip()
+        else:
+            if self.client_secret is None:
+                raise MastodonIllegalArgumentError('Specified client id directly, but did not supply secret')
+
         if self.access_token is not None and os.path.isfile(self.access_token):
             with open(self.access_token, 'r') as token_file:
                 self.access_token = token_file.readline().rstrip()