v1.0.16: Merge pull request #44 from mskoryh/master

Replaced deprecated method for new versions of PhpSpreadsheet.

v1.0.15

Code refactoring. Added Export to Pdf. Well, nothing has changed in fact.

v1.0.14

Fixed ReferenceHelper.php on modern version of PhpSpreadsheet.

v1.0.11

Translated comments into English, fixed some minor bugs.

v1.0.10

Added support .ods and .xls files. And addes events for additional customizing. Added samples of the innovations.

1.0.9

fixed formulas in rendered file