Add trunc helper function

[sentriz]

hello, this adds a trunc() helper function to truncate long text
eg. on my statusbar where there is limited space I could shorted long track names
eg

$ playerctl metadata -f '{{lc(status)}} "{{title}}"'
playing "Doctor Blowfin's Water Cruiser"
$ playerctl metadata -f '{{lc(status)}} "{{trunc(title, 25)}}"'
playing "Doctor Blowfin's Water Cr…"

if you'll accept this PR I can update it for docs/readme/etc

thanks!

[acrisci]

Looks like a quality submission. I need tests and documentation to release it.

[sentriz]

hey, I added some tests and updated the readme/man page

[acrisci]

👍

[timvisee]

I'd love to see a new version release including this change. Any info on when we might expect a new release?

[acrisci]

Yeah I think I can release soon.