#20 MFS fits files are missing WS* keywords in wideband mode

[André Offringa]

The MFS fits files created in wideband mode don't have the WSClean specific fits keywords:

[nhw573@raijin6 1069415952]$ fitshdr 1069415952_deeper-0001-XX-image.fits | grep WS
ORIGIN  = 'WSClean '           / W-stacking imager written by Andre Offringa
WSCDATAC= 'CORRECTED_DATA'
WSCWEIGH= 'Briggs''(-1)'
WSCCHANE=                 768.
WSCCHANS=                 576.
WSCFIELD=                   0.
WSCGAIN =                  0.1
WSCGKRNL=                   7.
WSCIMGWG=             2174483.
WSCMAJOR=                   4.
WSCMGAIN=                 0.85
WSCMINOR=               50000.
WSCNEGCM=                   1.
WSCNEGST=                   1.
WSCNITER=               50000.
WSCNWLAY=                  16.
WSCSMPSF=                   0.
WSCTHRES=      0.0453390993117

[nhw573@raijin6 1069415952]$ fitshdr 1069415952_deeper-MFS-XX-image.fits | grep WS
ORIGIN  = 'WSClean '           / W-stacking imager written by Andre Offringa
WSCIMGWG=             9177197.

Reported by N. Hurley-Walker

[André Offringa]

Solved for 1.5.