[core] restructure to allow PIP packaging

OK - so I have to admit I *hate* the fact that PIP seems to require a
subdirectory named like the library.

But since the PIP package is something really nifty to have (thanks to
@tony again!!!), I updated the codebase to hopefully conform with what
PIP expects. Testruns so far look promising...

bumblebee_status/modules/contrib/notmuch_count.py

@@ -0,0 +1,51 @@
+# pylint: disable=C0111,R0903
+
+"""Displays the result of a notmuch count query
+   default : unread emails which path do not contained 'Trash' (notmuch count 'tag:unread AND NOT path:/.*Trash.*/')
+
+Parameters:
+    * notmuch_count.query: notmuch count query to show result 
+
+Errors:
+    if the notmuch query failed, the shown value is  -1
+
+Dependencies:
+    notmuch (https://notmuchmail.org/)
+
+contributed by `abdoulayeYATERA <https://github.com/abdoulayeYATERA>`_ - many thanks!
+"""
+
+import os
+
+import core.module
+import core.widget
+
+import util.cli
+
+
+class Module(core.module.Module):
+    def __init__(self, config, theme):
+        super().__init__(config, theme, core.widget.Widget(self.output))
+
+        self.__notmuch_count_query = self.parameter(
+            "query", "tag:unread AND NOT path:/.*Trash.*/"
+        )
+
+    def output(self, widget):
+        return self.__notmuch_count
+
+    def state(self, widgets):
+        if self.__notmuch_count == 0:
+            return "empty"
+        return "items"
+
+    def update(self):
+        try:
+            self.__notmuch_count = util.cli.execute(
+                "notmuch count {}".format(self.__notmuch_count_query)
+            ).strip()
+        except Exception:
+            self.__notmuch_count = "n/a"
+
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4