Handle parameter values with multiple entries

[onny]

Fixing parser for quoted multi-value parameters. The PR fixes the string length detection of this parameter in case if it's not a simple single string but an array.

attendee = ICAL.Property.fromString(
  'ATTENDEE;MEMBER="mailto:mygroup@localhost","mailto:mygroup2@localhost":mailto:user2@localhost'
);
console.log(attendee);

Will now correctly return the attendee URI mailto:user2@localhost

Fixes https://github.com/kewisch/ical.js/issues/634

[coveralls]

Pull Request Test Coverage Report for Build 9484426386

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

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Details

• 10 of 10 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.002%) to 98.164%

---

Totals
Change from base Build 9390039473:	0.002%
Covered Lines:	9369
Relevant Lines:	9530

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 12623102307

Details

• 15 of 15 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.002%) to 98.189%

---

Totals
Change from base Build 12622818924:	0.002%
Covered Lines:	9522
Relevant Lines:	9684

---

💛 - Coveralls

[kewisch]

Thanks for the patience and taking care of the comments!