jp: dark and light theme:

- `background` setting can now be used in sat.conf to indicate if the terminal use a
  `dark` or a `light` colour
- if `background` is not set or set to `auto`, the background colour is autodetected
- Jp.get_config (or CommandBase.get_config) method can now be used to retrieve a setting

sat_frontends/jp/common.py

@@ -126,7 +126,6 @@ class BaseEdit(object):
             and vice versa
         """
         self.host = host
-        self.sat_conf = config.parseMainConf()
         self.cat_dir = cat_dir
         self.use_metadata = use_metadata