Publish all ephemeris on init then revert to ONCHANGED

Most applications need to build a data base, and this doesn't happen immediately if ONNEW/ONCHANGED is selected. No ephems are obtained until an SV drops in/out. ONTIME gets obnoxious and ties up bandwidth because rarely will those messages be useful. we should have a one-off blast of everything it sees on init then rever to ONCHANGED.
