fix pseudo packages obsoleting other pseudo packages

This was broken with commit #ea033e29, which fixed pseudo packages
obsoleting real packages.
Always return IGNORE for pseudo packages in RPM_ONLY mode

The example codes already expect this behavior.
change last commit to check for SOLVER_TRANSACTION_KEEP_PSEUDO
fix bug in solver_get_unneeded that could lead to an endless loop
fix typos in pool_job2str
make addfilelist more resistant against corrupt rpms
add changes, bump version