CRAN version 0.2.1

Major changes:

• Add dodgr_isochrones, dodgr_isodistances, and dodgr_isoverts functions
• Considerable speed-ups for dodgr_flows_aggregate and dodgr_flows_disperse

Minor changes:

• dodgr_flows_disperse allows k to be a vector, with different coefficients for each from point.
• Add "highway:pedestrian" to weighting profiles
• weight_streetnet for sc objects automatically adds component column
• bug fix in weight_streetnet.sc(..., wt_profile = 1)
• bug fix in dodgr_full_cycles for SC class objects