Fix HTML entities.

[clauswilke]

This closes #89. HTML entities now work.

library(marquee)

cat(marquee_parse("- -")$text[2])
#> - -
cat("-\u00A0-") # correct code for non-breaking space
#> - -

cat(marquee_parse("->-")$text[2])
#> ->-
cat("-\u003E-") # correct code for > sign
#> ->-

cat(marquee_parse("-𝔄-")$text[2])
#> -𝔄-
cat("-\uD835\uDD04-") # correct code for capital A fractur
#> -𝔄-

^{Created on 2025-09-19 with reprex v2.1.1}

[clauswilke]

Apologies for accidentally committing an R project file. Let me know if I should remove it.