PSFMag vs TrailedSourceMag offset for MBAs

[bernardinelli]

Even for MBAs, the PSFMag and TrailedSourceMag are significantly different - this is the cause for the 0.02 offset in the G coefficient for the phase curve fits seen in DP0.3 (that uses PSFMags)

[mschwamb]

A better name of trailedsourcemag or an alias such as asteroidmag that ppoints to trailedsourcemag would be helpful so users don't make the mistake of using PSF mag - it matters

[mschwamb]

TrailedSourceMag is not actually in any of the Solar System database schema according to the DPDD so I think that needs to be added