v3.15.0

UniPDF v3.15.0

New minor release of UniPDF contains new features.

New features:

• Support for custom document properties and metadata [USD-35, UP-111]
  AddCustomInfo function for PdfInfo to set own custom properties.
  New example for setting custom metadata: https://github.com/unidoc/unipdf-examples/blob/master/metadata/pdf_metadata_set_docinfo.go
  Updated and simplified example for getting metadata: https://github.com/unidoc/unipdf-examples/blob/master/metadata/pdf_metadata_get_docinfo.go