Visibility settings for custom metadata columns are now remembered for the duration of the Administrator instance.

Clean up the table and columns when leaving the message browser.

Preferences are no longer saved for custom metadata columns when their visibility is changed.

Reduced visibility of static Message Browser column numbers to protected because nothing more is needed.
Issue: MIRTH-2361
Added option to set charset when sending emails via SMTPConnection

Updated reference list factory to show method signature including charset

Updated commons-email jar to 1.3.1
Issue: MIRTH-1911
Updated XStream for command line interface and server manager.
Issue: MIRTH-2734
MIRTH-2239: Added global and global channel map replacement support to all connector plugin services. The API invokeConnectorService call has changed now to take in the channel ID as well to allow for global channel replacement. Each connector service (where applicable) has been updated to use a TemplateValueReplacer and replace appropriate values before doing whatever it needs to.