Use stdout for startup banner for consistency

[d-torrance]

Currently we use a hodgepodge. The M2 version info is on stderr and the help info is on stdout. We switch it so that everything is stdout.

Before

$ M2 -e "exit 0" > /dev/null
Macaulay2, version 1.25.11-77-g620ed82f51 (development)
$ M2 -e "exit 0" 2> /dev/null
Type "help" to see useful commands

After

$ M2 -e "exit 0" > /dev/null
$ M2 -e "exit 0" 2> /dev/null
Macaulay2, version 1.25.11-73-gc0c0867784 (mutable-list)
Type "help" to see useful commands