v0.4.0

• Fix weekday labels not always having same exact width
• Add support for complex attribute dates. Closes #7 and #12.
• Add support for attribute excludeDates, date picker availableDates. Closes #19.
• Add support for endless date ranges using null for start/end dates. Closes #20.
• Add support for attaching custom data to attributes via customData property. Closes #21.
• Add Turkish locale.