use buffer size, fix media enclosures, fix names

- use the buffer size of downloaded media instead of content length
  (shouldv'e done so in the first place)

- allow multiple media enclosures

- replace special chars for filenames

add note about mime type detection

prefer enclosures before GUID for media

bump deps

add build badge

fix module name && update deps

fix package path typo

replace github

use custom import path for neinp

fix git path in documentation

add .build.yml

go modulize

use sr.ht neinp imports

fix usage in readme

initial commit