Breaks deal with ranges more consistently

[teunbrand]

This PR aims to fix #518.

Briefly:

• We always call range() on the input to deal with length >2 data.
• Non-finites are always removed from the range.
• Length 0 in, length 0 out.
• Length 1 or zero-range in, first element out

Reprex from issue:

devtools::load_all("~/packages/scales/")
#> ℹ Loading scales

good <- c(1, 20)
bad <- c(1, 10, 20)

scales::breaks_extended(n=5)(good)
#> [1]  0  5 10 15 20
scales::breaks_extended(n=5)(bad)
#> [1]  0  5 10 15 20

scales::breaks_width(width=5)(good)
#> [1]  0  5 10 15 20
scales::breaks_width(width=5)(bad)
#> [1]  0  5 10 15 20

scales::breaks_exp(n = 5)(good)
#> [1] 20 19 18 17  0
scales::breaks_exp(n = 5)(bad)
#> [1] 20 19 18 17  0

scales::breaks_log(n = 5)(good)
#> [1]  1  3 10 30
scales::breaks_log(n = 5)(bad)
#> [1]  1  3 10 30

scales::breaks_pretty(n=5)(good)
#> [1]  0  5 10 15 20
scales::breaks_pretty(n=5)(bad)
#> [1]  0  5 10 15 20

scales::breaks_timespan(unit = "mins")(good)
#> Time differences in secs
#> [1]    0  240  480  720  960 1200
scales::breaks_timespan(unit = "mins")(bad)
#> Time differences in secs
#> [1]    0  240  480  720  960 1200

^{Created on 2025-11-13 with reprex v2.1.1}