[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/memory.py

@@ -0,0 +1,77 @@
+# pylint: disable=C0111,R0903
+
+"""Displays available RAM, total amount of RAM and percentage available.
+
+Parameters:
+    * memory.warning : Warning threshold in % of memory used (defaults to 80%)
+    * memory.critical: Critical threshold in % of memory used (defaults to 90%)
+    * memory.format: Format string (defaults to '{used}/{total} ({percent:05.02f}%)')
+    * memory.usedonly: Only show the amount of RAM in use (defaults to False). Same as memory.format='{used}'
+"""
+
+import re
+
+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.memory_usage))
+        core.input.register(
+            self, button=core.input.LEFT_MOUSE, cmd="gnome-system-monitor"
+        )
+
+    @property
+    def _format(self):
+        if util.format.asbool(self.parameter("usedonly", False)):
+            return "{used}"
+        else:
+            return self.parameter("format", "{used}/{total} ({percent:05.02f}%)")
+
+    def memory_usage(self, widget):
+        return self._format.format(**self._mem)
+
+    def update(self):
+        data = {}
+        with open("/proc/meminfo", "r") as f:
+            for line in f:
+                tmp = re.split(r"[:\s]+", line)
+                value = int(tmp[1])
+                if tmp[2] == "kB":
+                    value = value * 1024
+                if tmp[2] == "mB":
+                    value = value * 1024 * 1024
+                if tmp[2] == "gB":
+                    value = value * 1024 * 1024 * 1024
+                data[tmp[0]] = value
+        if "MemAvailable" in data:
+            used = data["MemTotal"] - data["MemAvailable"]
+        else:
+            used = (
+                data["MemTotal"]
+                - data["MemFree"]
+                - data["Buffers"]
+                - data["Cached"]
+                - data["Slab"]
+            )
+        self._mem = {
+            "total": util.format.byte(data["MemTotal"]),
+            "available": util.format.byte(data["MemAvailable"]),
+            "free": util.format.byte(data["MemFree"]),
+            "used": util.format.byte(used),
+            "percent": float(used) / float(data["MemTotal"]) * 100.0,
+        }
+
+    def state(self, widget):
+        if self._mem["percent"] > float(self.parameter("critical", 90)):
+            return "critical"
+        if self._mem["percent"] > float(self.parameter("warning", 80)):
+            return "warning"
+        return None
+
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4