Remove obsolete variables

[remkos]

Obsolete variables to be removed are:

topo_dtm2000
topo_dtu10
tide_ocean_fes04
tide_load_fes04
tide_ocean_got48
tide_load_got48
iono_iri2007
wave_m0
wave_m1
wave_m2
wave_m4
wave_shs
mss_comb15
mss_cnes_cls11
mss_dtu13
topo_srtm30plus
alt_std1204
alt_std1404
swh_ww3

To be applied to:

• c2 -C5-184
• g1
• gs
• pn
• sa -C1-114
• sw -C103-313
• tx

To be covered through full reprocessing:

• 3a
• 3b
• 6a.hr
• 6a.lr
• e1
• e2
• j3
• j1
• j2
• n1