do no lowercase first letter of allcaps keyword (#624)

fixing #623: Don't lower-case the first character of a keyword argument when the entire segment is upper case.

Author: rndblnch

pyobjc-core/Lib/objc/_transform.py

@@ -43,7 +43,8 @@ def _selectorToKeywords(selector):
     parts = selector.split(":")[:-1]
     if parts[0].startswith("With"):
         parts[0] = parts[0][4:]
-    parts[0] = parts[0][:1].lower() + parts[0][1:]
+    if len(parts[0]) > 1 and not parts[0][1].isupper():
+        parts[0] = parts[0][:1].lower() + parts[0][1:]
 
     return tuple(parts)