maplegend_0.6.0

fix

• use only one lwd and border value in "prop" type legends
• use box_cex in "symb" legend to fine tune spacing between symbols
• better spacing between boxes and NA box in "choro" horizontal legends
• apply box_cex to na symbols for type = "symb"
• better defaults for "symb"
• better proportional symbols display
• test for and allow one modality legends (#7)
• correct a bug of text overflow with type = "symb" and no_data = TRUE (#8)
• correct border color assignement for type "symb"

feat

• add a val_max arg to adjust the proportionnal symbols ma size to a specific
  value when using type = "prop"
• new legend type "choro_point" for choropleth legends on circles or squares
• new legend type "choro_line" for choropleth legends on lines
• new legend type "choro_symb" for choropleth legends on symbols
• new legend type "typo_line" for typology legend on lines.