Confusing and contradictory licensing information

[ArrayBolt3]

Expected Behavior

Licensing info in lximage-qt's source code should be consistent and easy to understand.

Current Behavior

Licensing info is confusing and in some places contradictory.

Steps to Reproduce (for bugs)

1. View the AUTHORS file. The license is specified as "GPL-2+ and LGPL-2.1+". From the perspective of a copyright auditor, this means that a user must comply with the terms of both the GPLv2 (or any later version) and the LGPLv2.1 (or any later version). This was probably intended to be a summary, not a combination of licenses, but it has the effect of combining the licenses.
2. View data/lximage-qt.metainfo.xml. The <project_license> tag specifies GPL-2.0-only. This doesn't match with the earlier declaration of GPL-2+.
3. cd into the src directory and run grep -r -i "LGPL" and grep -r -i "Lesser". There doesn't appear to be any occurrence of the LGPL license anywhere in the lximage-qt codebase.

Suggested fix

1. Change the <project_license> tag in data/lximage-qt.metainfo.xml to GPL-2.0-or-later.
2. Change AUTHORS to specify GPL-2+ as the repo-wide license and add an explicit LGPL-2.1+ license header to files that are intended to be usable under that license.

[tsimonq2]

Ubuntu and Debian are particularly strict about consistent licensing. If we find anything else in the LXQt source code, we'll be sure to let you know. Otherwise, we'd appreciate a simple and smooth remedy for this.

Thank you very much for your time!