Improve error message when encountering unmapped memories in a partition solved and using SBY

[jix]

The SBY strategy uses xprop by default and xprop currently requires the memory to be mapped. The solution is to add memory_map -formal, but the error message that points to a memory is hidden in the SBY logfile. Since EQY knows which partitions contain memory it could produce a better error and/or just take care of mapping the memory.