[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/core/layout-xkb.py

@@ -0,0 +1,71 @@
+# pylint: disable=C0111,R0903
+
+"""Displays the current keyboard layout using libX11
+
+Requires the following library:
+    * libX11.so.6
+and python module:
+    * xkbgroup
+
+Parameters:
+    * layout-xkb.showname: Boolean that indicate whether the full name should be displayed. Defaults to false (only the symbol will be displayed)
+    * layout-xkb.show_variant: Boolean that indecates whether the variant name should be displayed. Defaults to true.
+"""
+
+from xkbgroup import *
+
+import logging
+
+log = logging.getLogger(__name__)
+
+import core.module
+import core.widget
+import core.input
+
+import util.format
+
+
+class Module(core.module.Module):
+    def __init__(self, config, theme):
+        super().__init__(config, theme, core.widget.Widget(self.current_layout))
+
+        core.input.register(self, button=core.input.LEFT_MOUSE, cmd=self.__next_keymap)
+        core.input.register(self, button=core.input.RIGHT_MOUSE, cmd=self.__prev_keymap)
+        self.__show_variant = util.format.asbool(self.parameter("show_variant", True))
+
+    def __next_keymap(self, event):
+        self.__set_keymap(1)
+
+    def __prev_keymap(self, event):
+        self.__set_keymap(-1)
+
+    def __set_keymap(self, rotation):
+        xkb = XKeyboard()
+        if xkb.groups_count < 2:
+            return  # nothing to do
+        layouts = xkb.groups_symbols
+        idx = layouts.index(xkb.group_symbol)
+        xkb.group_symbol = str(layouts[(idx + rotation) % len(layouts)])
+
+    def current_layout(self, widget):
+        try:
+            xkb = XKeyboard()
+            log.debug("group num: {}".format(xkb.group_num))
+            name = (
+                xkb.group_name
+                if util.format.asbool(self.parameter("showname"), False)
+                else xkb.group_symbol
+            )
+            if self.__show_variant:
+                return (
+                    "{} ({})".format(name, xkb.group_variant)
+                    if xkb.group_variant
+                    else name
+                )
+            return name
+        except Exception as e:
+            print("got exception: {}".format(e))
+            return "n/a"
+
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4