Refactor the EDM4hep to LCIO conversion to make it more consistent with the other direction

[tmadlener]

BEGINRELEASENOTES

• Rename all convXYZ methods to convertXYZ and deprecate the former versions for the EDM4hep to LCIO direction to make it more consistent with the other direction.
• Cleanly split the EDM4hep to LCIO conversion into two steps, doing data conversion only in the first step and relation resolving in a second step.
  • Introduce resolveXYZRelations functions for all types where it is necessary and remove preliminary relation resolving from data conversion functions
  • All convertXYZ functions now only take one map that is populated as they no longer have to do any relation resolving
• Add roundtrip tests for ReconstructedParticle conversion
  • Fix issue that was lurking here in passing by cleanly splitting conversion process into two steps

ENDRELEASENOTES

This is mainly a preparatory step to make #51 a bit easier to do and to have a bit more consistency between the different conversion directions.

• Includes Enable compiler warnings and fix them #53