New MLDonkey release 2.7.3

- add GeoIP database support
This product includes GeoLite data created by
MaxMind, available from http://maxmind.com/
- change file opening mechanism, open rw only when needed
- EDK: add more server info fields
- Fix thread recognition on *BSD
- web_infos: save downloaded files and re-download only when newer versions are available
- search results are updated if higher values for available/complete_sources are found
- EDK: Avoid LowID if max_indirect_connections is reached, servers calling back always get a connection