Bug: incorrect highlight of dates in range Calendar

[berdyshev]

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[x] bug report
[ ] feature request
[ ] support request => Please do not submit support request here, instead see http://forum.primefaces.org/viewforum.php?f=57

Current behavior
When selecting range in the Calendar component starting in one month and ending in next one the highlight of selected dates is incorrect.

Expected behavior
Correctly highlight range across months.

Minimal reproduction of the problem with instructions
https://codesandbox.io/s/9okpx3o80r

• React version: 16.2

• PrimeReact version: 1.5.0

• Browser: [all ]

• Language: [ES6/7]