fix double WEEKLY string in to_ical result

[pawelnguyen]

Hello :)

I was trying to generate iCal format from schedule which I earlier loaded from yaml. I stumbled across FREQ=WEEKLY,WEEKLY results from to_ical. They are incompatible with google calendar to which I tried to import my calendar, and probably with RFC (I didn't check that).
After a bit of digging I found that WeeklyRule has doubled interval values which happens while loading yaml. I wrote a test and fixed it, let me know if it needs refactoring :)

[pawelnguyen]

not sure if description is understandable, to reproduce the problem:

schedule = Schedule.new
schedule.add_recurrence_rule WeeklyRule.new
schedule2 = Schedule.from_yaml(schedule.to_yaml)
p schedule.to_ical
#"DTSTART;TZID=CET:20130329T154100\nRRULE:FREQ=WEEKLY"
p schedule2.to_ical
#"DTSTART;TZID=CET:20130329T154100\nRRULE:FREQ=WEEKLY,WEEKLY" 

[avit]

Thanks @pawelnguyen, I'll have a look and see about merging this into a release this week.

[aaroncraigongithub]

I'm having the same problem.
A simpler test case is:

rule = Rule.weekly
rule.to_ical
# "FREQ=WEEKLY"
rule.interval(3)
rule.to_ical
# "FREQ=WEEKLY,WEEKLY;INTERVAL=3;WKST=SU"

[avit]

The problem here looks like the same as #158. I've addressed them both together.