The Date Repeat module’s date_repeat_build_dates() function does not support
RDATEs and EXDATEs defined as separate properties, as well as being a bit
buggy in other ways. So I copy-pasta’d it and made the necessary fixes.

I wanted to add support for EXRULEs, but it’s more complicated than I
expected. So since no one has actually asked for it, I left it as a TODO.

This commit adds the migration code that converts all Feeds Importers which used
the DateIcalIcalcreatorParser plugin to use DateiCalFeedsImporter instead. The
old classes have been removed.

I hadn't yet tested the RRULE import code when I first pushed Date iCal 3.x-dev,
but now I have. It's much more robust than it was in 2.x.

In addition, I moved the parsing class out of DateiCalFeedsParser.inc and into
libaries/ParserVcalendar.inc, which is like how Feeds' own CSV parser is set up.

This new version is still in a state of partial completeness. You may need to do
some manual fixing to get it working, due to a change I made in the classes
offered by this module. Try 'drush cc registry' if 'drush cc all' fails.

Please note that ALL of the hooks exposed by Date iCal have changed. They do
essentially the same things they used to do, but they're named differently.

The big change is that the Feeds plugin has been completely re-written to
conform to the Feeds APIs. It's now much more resilient and powerful. Feeds
Tamper will now work, and is in fact the prescribed way to alter data, since I
removed several alter hooks.

Issue [#2046935]: Added support for "long text" and "long text and summary" for the LOCATION and SUMMARY fields.

Added a version number to help me determine which version of Date iCal is being used by something who's having problems.

Added the hook_date_ical_post_render() alter hook.

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
boundries.

I added the summary_field option to option_definition, which should
fix several (surprisingly unreported) errors related to Features and first-time
setup.

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.

Issues [#1931020] and [#1935820]: Allow custom fields for summary. Fix repeating events causing duplicates. Add @file to DateIcalFeedsParser.inc

Applied patch #11 from [#1922658] to get around iCalcreator limitation with stream wrappers. Also made the amount of whitespace on blank lines consistent throughout the project.

- Issue #1529506, Added optional webcal:// support.
- Issue #1890736, Added ability to exclude the X-WR-CALNAME property.
- Issue #1565410, Sites with "Clean URLs" disabled can now download feeds normally.
- Several minor bigfixes, and cleanup of the iCal icon theming.