Spelling, Overrides, and unneeded method call

Add API for PreferencesManagers to initialize with errors, so they are
in a state that can be checked so follow on managers can refuse to
initialize as well.

Also take steps to ensure a manager is not initialized more than once
if initialized with errors.
Errors are displayed in the order they occur.

The real error is *always* shown in a separate dialog because the
XmlAdapters use a different mechanism for displaying those errors and
will not propagate them up the call stack.
Also provide constructor to create an InitializationException purely
from a cause.

The StartupManager now does a two step process for loading its
preferences. It loads all preferences into memory (creating the list of
actions available in the preferences window) and then, if there were
not errors blocking it, performs those actions.

To make this work, the triggers for startup actions were moved from the
XmlAdapters that load the actions to the StartupModels themselves. Some
actions still need to throw nicer error messages, but this generally
works now.

If a startup action is not valid, do not perform it.