In the November developer meeting, Christian and I agreed that
it's best to remove that offending LUID specifications altogether.
Those embedded LUIDs where one of the issues blocking the transition to C++11
lib::Depend<TY> works as drop-in replacement for lib::Singleton<TY>
This changeset removes the convoluted special cases like
SingletonSub and MockInjector.
lumiera_error_set() now takes an optional extra string which can be used
to pass context relevant data along. This string gets copied into the
error state so one can easily create it by the tmpbuf_snprintf() facility.
Also a lot of places which define errors get fixed according to this.
