Rework alert module

[mrrogge]

I had some ideas for making the alert module more useful:

1. The developer should be able to define custom alert messages and assign them to IDs. These alerts could then be raised by calling the module as a function and passing in the corresponding IDs.
2. Each custom alert should have a configurable property that defines what happens when it is called. One mode could raise an error, another could print the message to the console, another could write out to a log file, and another could just do nothing.