- introduce and test BccSelf config, to prevent bcc-self on outgoing mails

- introduce context.get_config_int() which respects default values
  declared in config.rs (Config)

src/config.rs

@@ -30,6 +30,8 @@ pub enum Config {
     Selfstatus,
     Selfavatar,
     #[strum(props(default = "1"))]
+    BccSelf,
+    #[strum(props(default = "1"))]
     E2eeEnabled,
     #[strum(props(default = "1"))]
     MdnsEnabled,
@@ -92,6 +94,14 @@ impl Context {
         }
     }
 
+    pub fn get_config_int(&self, key: Config) -> i32 {
+        self.get_config(key).and_then(|s| s.parse().ok()).unwrap()
+    }
+
+    pub fn get_config_bool(&self, key: Config) -> bool {
+        self.get_config_int(key) != 0
+    }
+
     /// Set the given config key.
     /// If `None` is passed as a value the value is cleared and set to the default if there is one.
     pub fn set_config(&self, key: Config, value: Option<&str>) -> Result<(), Error> {