Replace wildcard imports in git.refs

This uses explicit imports rather than wildcard imports in git.refs
for names from its submodules.

A comment indicated that the import order was deliberate, but each
of the modules being imported from defined __all__ and there was no
overlap in the names across any of them. The other main reason to
import in a specific order is an order dependency in the side
effects, but that does not appear to apply, at least not at this
time. In addition, this adds explicit imports for the the Python
submodules of git.refs so it is clear that they can always be
accessed directly in git.refs without furhter imports if desired.
For clarity, that appears first, and it makes the order of the
"from" imports not relevant to such side effects (due to the "from"
imports no longer causing modules to be loaded for the first time).

Author: EliahKagan

git/refs/__init__.py

@@ -1,12 +1,28 @@
 # This module is part of GitPython and is released under the
 # 3-Clause BSD License: https://opensource.org/license/bsd-3-clause/
 
-# Import all modules in order, fix the names they require.
+__all__ = [
+    "head",
+    "log",
+    "reference",
+    "remote",
+    "symbolic",
+    "tag",
+    "HEAD",
+    "Head",
+    "RefLog",
+    "RefLogEntry",
+    "Reference",
+    "RemoteReference",
+    "SymbolicReference",
+    "Tag",
+    "TagReference",
+]
 
-from .symbolic import *  # noqa: F401 F403
-from .reference import *  # noqa: F401 F403
-from .head import *  # noqa: F401 F403
-from .tag import *  # noqa: F401 F403
-from .remote import *  # noqa: F401 F403
-
-from .log import *  # noqa: F401 F403
+from . import head, log, reference, remote, symbolic, tag
+from .head import HEAD, Head
+from .log import RefLog, RefLogEntry
+from .reference import Reference
+from .remote import RemoteReference
+from .symbolic import SymbolicReference
+from .tag import Tag, TagReference