Optimized when using station list. Uses cached VprofPlot.

Summary: This deals with preformance problems with big stations lists and redrawing.

Test Plan: Has been tested at SMHI with gribfiles. Should be tested with profiles in nedcdf format.

Reviewers: #diana, lisbethb

Reviewed By: #diana, lisbethb

Subscribers: lisbethb, #diana

Differential Revision: https://phab.met.no/D86