Introduce IItem::getVariantBase()

[richardhj]

Description

Introduce the IItem::getVariantBase() as described in #237.

Unit tests for IItem::getVariants(), IItem::isVariant(), IItem::isVariantBase(), IItem::getVariantBase() unneeded?

Checklist

• Read and understood the CONTRIBUTING guidelines
• Created tests, if possible
• All tests passing
• Extended the README / documentation, if necessary
• Added myself to the @authors in touched PHP files
• Checked the changes with phpcq and introduced no new issues

[zonky2]

current year is 2017 ;-)

[discordier]

Unit tests for IItem::getVariants(), IItem::isVariant(), IItem::isVariantBase(), IItem::getVariantBase() unneeded?

Unit tests are always needed, however they are most times omitted because the dev was too lazy. 😄
I'd be happy if you could add them (and if possible even more) over the time.

[zonky2]

hi @richardhj it´s possible to write the unit test? we should merge the PR asap

[richardhj]

I'm not sure what the unit tests should cover.