Load alerts preferences from saved settings file

git-svn-id: svn://svn.code.sf.net/p/autowikibrowser/code/AWB@9277 5227b50d-9349-4574-b055-4b0a7525e11c
Ensure setting for last alert in list is correctly loaded

git-svn-id: svn://svn.code.sf.net/p/autowikibrowser/code/AWB@9278 5227b50d-9349-4574-b055-4b0a7525e11c
Enable alerts preferences, respect alerts preferences when generating alerts
For compatibility: for existing settings files, where no alerts will be recorded as selected, assume all alerts are selected if none in settings. Consequence: user cannot deselect all alerts as this will be treated as all selected. At a later date, once users have migrated over settings files, remove logic around this in AlertPreferences in Preferences.cs, to allow users to select no alerts, but enforce that use of old settings files will mean no alerts are enabled until the user manually changes the alerts preferences.

git-svn-id: svn://svn.code.sf.net/p/autowikibrowser/code/AWB@9279 5227b50d-9349-4574-b055-4b0a7525e11c
Ensure dictionaries of error items for highlighting are cleared down each time article info is processed, otherwise if alert has been used then disabled errors from earlier may be reported again

git-svn-id: svn://svn.code.sf.net/p/autowikibrowser/code/AWB@9280 5227b50d-9349-4574-b055-4b0a7525e11c
Typo and spacing

git-svn-id: svn://svn.code.sf.net/p/autowikibrowser/code/AWB@9281 5227b50d-9349-4574-b055-4b0a7525e11c