Merge pull request
#921 from minrk/traiterror
Show invalid config message on TraitErrors during initialization.
implemented via `@catch_config` decorator
Now, the event that was triggered by invalid app config (see `--log-level 5`) is triggered by bad config at any point during initialization.
This *will* catch TraitError-raising bugs in IPython itself, but only during initialization.
Also, deregister crash handler on use to avoid it being triggered recursively/repeatedly.
