[core] Rework core implementation

Experimental re-implementation of core functionality with the aim:
- Depend only on the Python Standard Library for core
- If modules are missing elsewhere, *never* throw
- Unit test *everything*
- Cleaner and more minimal implementation
- Better integration points for existing implementations (charts,
  braille, etc.)
- Full backwards-compatibility with existing module system (except where
  modules can be vastly simplified)

core/output.py

@@ -0,0 +1,16 @@
+import json
+
+class i3(object):
+    def start(self):
+        return '{}\n'.format(json.dumps({ 'version': 1, 'click_events': True }))
+
+    def stop(self):
+        return ']\n'
+
+    def begin_status_line(self):
+        return '['
+
+    def end_status_line(self):
+        return '],\n'
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4