Characters variables inherit same default behaviour as factors

[grantmcdermott]

Closes #321

pkgload::load_all("~/Documents/Projects/tinyplot/")
#> ℹ Loading tinyplot

set.seed(0)
x <- rep(c("A", "B", "C"), each = 20)
y <- runif(60)
gp <- sample(c("X", "Y", "Z"), size = 60, replace = TRUE)
df <- data.frame(x, y, gp)

plt(
  y ~ x | gp,
  data = df
)

I also addressed/enabled factor variable support for type_points().

plt(
  y ~ x | gp, pch = 0:2,
  data = df,
  type = type_points()
)

Note: the basic "p" type isn't working (I think b/c of #322).

plt(
  y ~ x | gp, pch = 0:2,
  data = df,
  type = "p"
)
#> Error in Summary.factor(structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, : 'range' not meaningful for factors

^{Created on 2025-02-17 with reprex v2.1.1}

[grantmcdermott]

(Will add NEWS etc. later tonight. Dinner time first.)