Sort the the MibLoaderLog.LogEntry instances before printing

[cederberg]

Reading a long list of MibLoaderLog.LogEntry instances is hard, since the entries are sorted by detection order, not their importance or location in the file.

Preferably, MibLoaderLog.entries() should return a sorted list of log entries, with errors first and warnings second. Inside each group, the entries should be sorted by file and line number.