Add Boost Serialization support for Conditions.
fixing merge conflicts from apfeiffer1:merge-test for boostio
added individual header files for externals to avoid inclusion problems
one more round of fixing issues with boost serialization.
Merge pull request #2124 from apfeiffer1/fixBioPart2

cleared out wrongly merged stuff from 7.0.x/7.1.x and fixed several serialisation issues