Add iconhd gas change event
Add iconhd gas change event

Signed-off-by: Tim Wootton <5ee0edb9e2229c0838f1959779f1949031de0123@tee-jay.demon.co.uk>

josh-wambua/libdivecomputer,henrik242/libdivecomputer,henrik242/libdivecomputer,josh-wambua/libdivecomputer,glance-/libdivecomputer,venkateshshukla/libdivecomputer,venkateshshukla/libdivecomputer,Poltsi/libdivecomputer-vms,glance-/libdivecomputer