get_source.sh update

[Mike Duigou]

Hello all;

I've pushed an update to the get_source.sh script which checks the version of the Mercurial client being used and rejects clients older than version 1.5. Version 1.5 was chosen as a cut-off because the reports of spuriously aborted transactions or stalled connections appear to be much higher with 1.4.1 and earlier. Version 1.1 and earlier don't appear to work at all with the current OpenJDK Mercurial server. Version 2.6.3 or later is recommended for best performance and reliability.

The script will be updated when the required or recommended version changes. This will probably happen very infrequently.

Mike