Demote sp and raster to suggests

[Robinlovelace]

Will speed up install times, could lead to future depreciation.

[Robinlovelace]

Bumped up priority list.

[Robinlovelace]

OK going to work on this after mentioning as a priority in #362

[Robinlovelace]

Work on this: #481

[Robinlovelace]

Some insight into dependencies in v1.8.7, x marks ones targetted for removal:

Imports:
    sp (>= 1.3.1), x
    curl (>= 3.2), x
    dplyr (>= 0.7.6),
    httr (>= 1.3.1),
    jsonlite (>= 1.5),
    stringr (>= 1.3.1),
    maptools (>= 0.9.3), x
    raster (>= 2.6.7), x
    rgeos (>= 0.3.28), x
    methods,
    geosphere (>= 1.5.7),
    Rcpp (>= 0.12.1),
    nabor (>= 0.5.0),
    rlang (>= 0.2.2),
    lwgeom (>= 0.1.4),
    sf (>= 0.6.3),
    magrittr,
    sfheaders,
    data.table,
    pbapply

dg = miniCRAN::makeDepGraph(pkg = "stplanr", includeBasePkgs = FALSE, suggests = FALSE)
plot(dg) # mass of pkgs

dg_betweenness = igraph::betweenness(dg)
summary(dg_betweenness)
#>    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
#>   0.000   0.000   0.000   1.879   2.792  19.500
class(dg_betweenness)
#> [1] "numeric"
dg_many = dg_betweenness > 1
# dg_small = igraph::delete_vertices(graph = dg, v = dg_many)
dg_small = igraph::induced_subgraph(graph = dg, which(dg_many))
plot(dg_small)

^{Created on 2022-04-03 by the reprex package (v2.0.1)}

[Robinlovelace]

geosphere and raster also import sp so must be made Suggests or removed.