This hook allows modules to fix broken timezone strings in the iCal feeds they import.
Also cleaned up the way that timezone strings are handled by the parser, especially under error conditions.
Cleaned up date_ical_format_text(), other bugfixes.
date_ical_format_text() was going way overboard on it's attempts
to make text iCal compliant. I got rid of all the escaping, and also
all the extra endlines which the drupal function was adding at 80-char
I added the summary_field option to option_definition, which should
fix several (surprisingly unreported) errors related to Features and first-time
Added the view object as a parameter for theme_date_ical_icon, which gives
additional context for any module that would like to override that theme.