Major upgrade and improvements for OPAC

What's Changed

• Update instructions by @rogercgui in #594
• Updates OPAC help by @rogercgui in #595
• Repairs in OPAC and more by @rogercgui in #596

Full Changelog: v3.1.2...v3.2.0

Actions by database administrator

The upgrade of the code can be done with the upgrade manager.

Upgrade of database content is not required, but there are updates in some database configuration folders

• Folder bases/lang/*
• Folder bases/opac_conf/*

Copy the relevant files from bases-examples_Linux or bases-examples_Windows to your installation

Note: If you are upgrading from v.3.0.0 or earlier then see the release notes of v3.1.2