Parse Raw Data without Caching and Networking

[giorgosneokleous93]

• Add a public API for parsing raw data. This allows users of the library to implement their own networking layer and caching. The change is compatible for both Kotlin and Java. https://github.com/prof18/RSS-Parser/commit/d269487b1b39b97f65725655156790af4bb9340f https://github.com/prof18/RSS-Parser/commit/82106f67e12541599e0fc02167b6633296b3393a
• Mark internal API with internal https://github.com/prof18/RSS-Parser/commit/0e95678fa958b989d5472a04d4b28f6466393dfb
• Updated README.md to include the new API
• Updated samplekotlin to include the parsing of raw data. Please see attached GIF for a demo. https://github.com/prof18/RSS-Parser/commit/3399a774ff0b2498df972784129afccee3f26c2f

[prof18]

Hi, thank you for the PR, I'm gonna review and merge asap!