my.stackexchange: use proper pip package, add stat

+ 'anonymous' mode for stat() function

my/stackexchange/stexport.py

@@ -0,0 +1,28 @@
+'''
+Stackexchange data
+'''
+REQUIRES = [
+    'git+https://github.com/karlicoss/stexport',
+]
+
+# TODO use GDPR?
+
+from stexport import dal
+from my.config import stackexchange as config
+
+
+# todo lru cache?
+def _dal() -> dal.DAL:
+    from ..core import get_files
+    inputs = get_files(config.export_path)
+    return dal.DAL(inputs)
+
+
+def site(name: str) -> dal.SiteDAL:
+    return _dal().site_dal(name)
+
+
+from ..core import stat, Stats
+def stats() -> Stats:
+    s = site('stackoverflow')
+    return stat(s.questions)