Add _ElementTree.iterfind() and _ElementTree.getelementpath() (GH-69)

Fixes #65
Fixes #66

Author: bockstaller

lxml-stubs/etree.pyi

@@ -238,10 +238,14 @@ class _ElementTree:
         self, path: str, namespaces: Optional[_NSMapArg] = ...
     ) -> List["_Element"]: ...
     def getpath(self, element: _Element) -> str: ...
+    def getelementpath(self, element: _Element) -> str: ...
     def getroot(self) -> _Element: ...
     def iter(
         self, tag: Optional[_TagSelector] = ..., *tags: _TagSelector
     ) -> Iterable[_Element]: ...
+    def iterfind(
+        self, path: str, namespaces: Optional[_NSMapArg] = ...
+    ) -> Iterator["_Element"]: ...
     def parse(
         self,
         source: _FileSource,