[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/network_traffic.py

@@ -0,0 +1,113 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""Displays network traffic
+   * No extra configuration needed
+
+contributed by `izn <https://github.com/izn>`_ - many thanks!
+"""
+
+import psutil
+import netifaces
+
+import core.module
+import core.widget
+
+import util.format
+
+WIDGET_NAME = "network_traffic"
+
+
+class Module(core.module.Module):
+    def __init__(self, config, theme):
+        widgets = [
+            core.widget.Widget(
+                module=self,
+                name="{0}.rx".format(WIDGET_NAME),
+                full_text=self.download_rate,
+            ),
+            core.widget.Widget(
+                module=self,
+                name="{0}.tx".format(WIDGET_NAME),
+                full_text=self.upload_rate,
+            ),
+        ]
+        super().__init__(config, theme, widgets)
+
+        self.widgets()[0].set("theme.minwidth", "0000000KiB/s")
+        self.widgets()[1].set("theme.minwidth", "0000000KiB/s")
+
+        try:
+            self._bandwidth = BandwidthInfo()
+
+            self._rate_recv = "?"
+            self._rate_sent = "?"
+            self._bytes_recv = self._bandwidth.bytes_recv()
+            self._bytes_sent = self._bandwidth.bytes_sent()
+        except Exception:
+            """ We do not want do explode anything """
+            pass
+
+    def state(self, widget):
+        """Return the widget state"""
+
+        if widget.name == "{}.rx".format(WIDGET_NAME):
+            return "rx"
+        elif widget.name == "{}.tx".format(WIDGET_NAME):
+            return "tx"
+
+        return None
+
+    def update(self):
+        try:
+            bytes_recv = self._bandwidth.bytes_recv()
+            bytes_sent = self._bandwidth.bytes_sent()
+
+            self._rate_recv = bytes_recv - self._bytes_recv
+            self._rate_sent = bytes_sent - self._bytes_sent
+
+            self._bytes_recv, self._bytes_sent = bytes_recv, bytes_sent
+        except Exception:
+            """ We do not want do explode anything """
+            pass
+
+    def download_rate(self, _):
+        return "{}/s".format(util.format.byte(self._rate_recv))
+
+    def upload_rate(self, _):
+        return "{}/s".format(util.format.byte(self._rate_sent))
+
+
+class BandwidthInfo(object):
+    """Get received/sent bytes from network adapter"""
+
+    def bytes_recv(self):
+        """Return received bytes"""
+        return self.bandwidth().bytes_recv
+
+    def bytes_sent(self):
+        """Return sent bytes"""
+        return self.bandwidth().bytes_sent
+
+    def bandwidth(self):
+        """Return bandwidth information"""
+        io_counters = self.io_counters()
+        return io_counters[self.default_network_adapter()]
+
+    @classmethod
+    def default_network_adapter(cls):
+        """Return default active network adapter"""
+        gateway = netifaces.gateways()["default"]
+
+        if not gateway:
+            raise "No default gateway found"
+
+        return gateway[netifaces.AF_INET][1]
+
+    @classmethod
+    def io_counters(cls):
+        """Return IO counters"""
+        return psutil.net_io_counters(pernic=True)
+
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4