ropensci/visdat: The Legend of LoFi

Minor Change

• Update vis_cor() to use perceptually uniform colours from scico package, using scico::scico(3, palette = "vik").
• Update vis_cor() to have fixed legend values from -1 to +1 (#110) using options breaks and limits. Special thanks to this SO thread for the answer
• Uses glue and glue_collapse() instead of paste and paste0
• adds WORDLIST for spelling thanks to usethis::use_spell_check()