Read the log level settings from the "loglevel" value in the
"bitmessagesettings" section of the config file. The possible
values map directly to the ones allowed by the logger module:
DEBUG, INFO, WARNING, ERROR, CRITICAL
Only allow these values, and cast to upper case to be more easy
going in the settings.
+ Add stderr capturing
+ Add identities and network status tabs
+ Add dialogs to configure identities
+ Add color pair definitions
+ Add the '-c' flag to use the curses interface
* Reorganize imports
* Switch logger to file_only mode when running with curses
