v1.4.2+ runs

[martinkilbinger]

Features to implement or change for upcoming runs of sp_validation for UNIONS SP catalogues versions 1.4.2 and higher:

• Output a catalogue with all metacal information (sheared values), no cuts applied, and all information to perform later cuts.
  Including N_EPOCH.
• Read maximask mask file(s) and add corresponding flags.
• Create example notebook to carry out metacal calibration.

Maybe later:

• Read in exposure mask file(s) and add corresponding flags.

Resolved by
#135 and #145

[martinkilbinger]

@cailmdaley @sachaguer @fabianhervaspeters