when dealing with double copy recalls.

Proper fix by defining a new RECALLJOB_SELECTED2NDCOPY state instead
of hijacking the (deprecated) fileTransactionId.

assignment operator of th Exception class.  Not only your friends
(classes) can play with your private parts (m_message and m_serrno) but
so can you.

    castor::exception::AlreadyInitialized

cancelled

resilient to hardware unavailability.

broken when dealing with double copy recalls.

This fix is not optimal: we're still using fileTransactionId being NULL
as a flag while we should really create an extra status
RECALLJOB_SELECTED2ND or SELECTEDSHADOW. Not on this hot fix...

This commit also includes a simpler way to select new recall candidates,
which makes it more immune to bugs like the above.
Plus a fix related to the precision used to check if a file was
overwritten while being recalled.

Added an std::exception::Backtrace class, providing a backtrace attached to all exception.
Fixed minor side effects (virtual destructors, catch orders) induced by the inheritance from std::exception.

namespace.

cancelled

C++ not be strict enough with the use of const.  I hope this commit fixes these
const problems.  There is still another SLC6 I need to tackle in order to get
TramCity to pass the SLC6 build.

until some work is pulled/rebased from the remote master.  Please also note
that more work still needs to be done before this can be used by somebody else.

the UUID should be passed in as a const.