Port Phoebe's part of vertex resolution

[yipengsun]

Phoebe's part contains the following

• [x] Apply vertex smearing
• [x] Recompute fit variables
• [x] Weight up/down tails of smear angle distributions as a variation

[yipengsun]

All implemented. The up/down weights look a bit suspicious though. Will check w/ Phoebe after she comes back.