more accurate treatment of state vs. serial vs. db;

more explicit check;

proper numa_nodes for build_worker;

tuned message;

tuned;

tuned signature;

support hosts with shared directory (e.g. NFS);

tuned message: failure may stem from build_cluster init;

proper sync_database for receive timeout;

clarified source structure;

tuned whitespace;

clarified command-line tools;

tuned output;

clarified signature;

tuned signature;

tuned signature;

proper sequential evaluation;

more robust command options;

performance tuning: avoid redundant db access;

clarified signature: proper treatment of implicit state (amending d0c9d277620e);

performance tuning: avoid redundant db access;

performance tuning: avoid multiple db roundtrips;

clarified signature: more robust treatment of implicit state;

proper sync_database for Database_Progress consumer; more efficient (but less reactive) Database_Progress.stopped;

tuned message;

tuned;

tuned messages;

tuned signature: removed unused arguments;

minor performance tuning: avoid multiple db roundtrips;

more operations;