Proposal: Allow REUSE compatible License Statements in License Policy

[Andreas Cord-Landwehr]

Hi, since no more comments came up, today I updated the licensing policy with 
the extensions to allow and even prefer SPDX markers in a way that is 
compatible with the REUSE.software specification:

https://community.kde.org/Policies/Licensing_Policy/

As noted in the thread, the following topics still need to be revisited in the 
policy and clarified:
- licensing of language updates by ScriptKiddy and other automatic tools
- better integration of Section 6 and Section 15 into the policy
- handling of big directories with resource files (e.g icons)

I still plan to look into them, but right now the top item on my priority list 
is to introduce SPDX markers into the KDE Frameworks. Meaning, if anybody 
wants to pick these topics up first, feel free :)

Cheers,
Andreas