Device config

Builds on #252.

Adds a configuration using a combo box. APNX page count algorithms are selected using the combo box. I'm proposing this as a different pull request so it can be reviewed. There is one issue I can see (below) but I'd rather not hold up the APNX changes (hence two pull requests to choose from).

One issue I can see (which appears to be the case regardless of these changes) is how it handles an existing user's device settings. OPT_APNX_ACCURATE is replaced with OPT_APNX_ACCURATE_METHOD. The original option was a bool and the new one is a string. Since the config is index (not name) based the new config will try to use "true" as the value for OPT_APNX_ACCURATE_METHOD causing a failure.