moved plugins out of the main libs source tree

- reduces file clutter
added first version of AUTHORS file

- based on 'git shortlog -sne' with some additional information from file headers etc
- known to be incomplete at this point
added LGPLv3 license file
added short copyright note to ./extern folder

- clarifies that those packages do not belong to EUDAQ and are (C) their respective copyright holders
added license text to manual
added AIDA acknoledgements to corresponding section in manual
added license to the README file
fixed path to example plugin in manual
added new EUDAQ logo

- svg is stored in ./etc/logo
- png version is now on the title page of the manual
Merge pull request #80 from hperrey/relicense

(Explicitly) putting EUDAQ under the LGPLv3 License