[modules] Separate modules into core & contrib

Also, improve errors when importing a module fails.

Also, add more tests.

modules/core/load.py

@@ -0,0 +1,38 @@
+# pylint: disable=C0111,R0903
+
+'''Displays system load.
+
+Parameters:
+    * load.warning : Warning threshold for the one-minute load average (defaults to 70% of the number of CPUs)
+    * load.critical: Critical threshold for the one-minute load average (defaults to 80% of the number of CPUs)
+'''
+
+import os
+import multiprocessing
+
+import core.module
+import core.input
+
+class Module(core.module.Module):
+    def __init__(self, config):
+        super().__init__(config, core.widget.Widget(self.load))
+        self._load = [0, 0, 0]
+        try:
+            self._cpus = multiprocessing.cpu_count()
+        except NotImplementedError as e:
+            self._cpus = 1
+        core.input.register(self, button=core.input.LEFT_MOUSE,
+            cmd='gnome-system-monitor')
+
+    def load(self, widget):
+        return '{:.02f}/{:.02f}/{:.02f}'.format(
+            self._load[0], self._load[1], self._load[2]
+        )
+
+    def update(self):
+        self._load = os.getloadavg()
+
+    def state(self, widget):
+        return self.threshold_state(self._load[0], self._cpus*0.7, self._cpus*0.8)
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4