Tagging version 3.2.0 3.2.0

fix #42 ZipFile::outputAsAttachment() gives empty zip

fix unknown zip software version

improved compatibility with php 7.4 and php-32 bit, minor bug fixes

Tagging hotfix 3.1.12 3.1.12

Tagging hotfix 3.1.11 3.1.11

Tagging hotfix 3.1.10 3.1.10

Tagging version 3.1.9 3.1.9

Tagging version 3.1.8 3.1.8

Tagging hotfix 3.1.7 3.1.7