Post 1.11.0, reconsider category support

[robertlipe]

See https://github.com/GPSBabel/gpsbabel/pull/1570/changes/f737a160b720a4574fbff39421b1a59a2008bc62..3fa362a27df665953fc56eb0087103f9f4b2d71e#r3025181704

Recommendation: remove the whole mess.