diff --git a/contrib/.gitignore b/contrib/.gitignore
index 33fa81ab6b..aa93cd250a 100644
--- a/contrib/.gitignore
+++ b/contrib/.gitignore
@@ -1,4 +1,9 @@
+*.pyc
+*.pyo
 /__init__.py
-/built/
+# These are files that are generated within the source tree by the
+# ppremake system.
 Makefile
 pp.dep
+/built/
+Opt?-*
diff --git a/direct/.gitignore b/direct/.gitignore
index 97b7fbcf49..aa93cd250a 100644
--- a/direct/.gitignore
+++ b/direct/.gitignore
@@ -1,4 +1,5 @@
 *.pyc
+*.pyo
 /__init__.py
 # These are files that are generated within the source tree by the
 # ppremake system.
diff --git a/direct/src/extensions_native/core_extensions.py b/direct/src/extensions_native/core_extensions.py
new file mode 100644
index 0000000000..3380dc3cf3
--- /dev/null
+++ b/direct/src/extensions_native/core_extensions.py
@@ -0,0 +1,28 @@
+import sys
+
+main_dir = Filename()
+
+if sys.argv and sys.argv[0]:
+    main_dir = Filename.from_os_specific(sys.argv[0])
+
+if main_dir.empty():
+    # We must be running in the Python interpreter directly, so return the CWD.
+    main_dir = ExecutionEnvironment.get_cwd()
+else:
+    main_dir.make_absolute()
+    main_dir = Filename(main_dir.get_dirname())
+ExecutionEnvironment.shadow_environment_variable('MAIN_DIR', main_dir.to_os_specific())
+del sys, main_dir
+
+
+def Dtool_funcToMethod(func, cls, method_name=None):
+    """Adds func to class so it is an accessible method; use method_name to specify the name to be used for calling the method.
+    The new method is accessible to any instance immediately."""
+    #if sys.version_info < (3, 0):
+    #    func.im_class = cls
+    func.im_func = func
+    func.im_self = None
+    if not method_name:
+        method_name = func.__name__
+    cls.DtoolClassDict[method_name] = func;
+
diff --git a/makepanda/.gitignore b/makepanda/.gitignore
index 94487b9516..c3667923e0 100644
--- a/makepanda/.gitignore
+++ b/makepanda/.gitignore
@@ -1 +1,2 @@
 *.pyc
+*.pyo
diff --git a/panda/.gitignore b/panda/.gitignore
index 3fbb4b2955..ec20cdb1ee 100644
--- a/panda/.gitignore
+++ b/panda/.gitignore
@@ -1,4 +1,5 @@
 *.pyc
+*.pyo
 # These are files that are generated within the source tree by the
 # ppremake system.
 Makefile