Merge pull request #190 from driventokill/feature/custom-field-names

feat: Support custom file name mappings

Merge pull request #124 from cavanwang/master

fix bug from issue 117 that 'Copy map with slice-type value panic'

Fix copier on v1.13

Ignore unexported fields

Fix copy from slice to single elem

Update README

Fix copy map with nested slice map

Fix copy map with nil interface

Fix deep copy slice of interface, close #89

Fix copy slice, close #88