add firebird 4 migration guide with instructions for old clients
add firebird 4 migration guide with instructions for old clients

https://ib-aid.com/download/docs/fb4migrationguide.html#_authorization_with_firebird_2_5_client_library_fbclient_dll

https://firebirdsql.org/file/documentation/release_notes/html/en/4_0/rlsnotes40.html#rnfb40-config-srp256
hgourvest/node-firebird