Consolidate Documentation from trema-core, trema-eclipse and trema-maven

[stadler]

Trema Core should contain documentation of all the core concepts of Trema.
Trema Eclipse should only contain documentation of the Eclipse UI Part of Trema.
Trema Maven should only contain documentation of the Maven Plugin.

Currently known documentations that are at the wrong place:

• http://netceteragroup.github.io/trema-eclipse/fileformat.html -> Sould be in Trema-Core
• http://netceteragroup.github.io/trema-eclipse/index.html -> Should be in Trema-Core

TODO:

• Check the documentation of all 3 projects and find further irregularities.
• Move the documentation to the correct projects and link to the corresponding configuration if needed.
• Redeploy the sites.