tertiary build-up + sting removal bug fix

tertiary is needed twice.

1. 1. sting removal
2. 2. bottom thinning
3. so, need a function
4. [vaa_pair, ca_vaa_btm] = tertiary(vaa_in, vaa_btm, vaa_out, common_range)

Sting removal fix

1. previously we use inner-bottom, outer-bottom pair without pairing up inner/outer,
   
2. this is wrong.
3. first, removal angular redundancy,
   
4. then, built tertiary,
5. finally, remove sting via w2z verification.