Add library publishing and update Gradle/Kotlin versions

[cypherdare]

This will allow SVG non-stop to be used as a project dependency via JitPack as explained in the updated README. It will take effect after tagging the pulled commit with "1.1.2" and then opening this Jitpack link to give JitPack a chance to build and publish it.

I tested Gradle assemble and the built application to confirm none of the Gradle changes affect current use of the app.

I updated the Gradle and Kotlin versions to help future-proof it.

[cypherdare]

*will take effect after creating a release named "1.1.2" before opening that Jitpack link.

By the way, I created this PR after I realized the project could easily be both an application and library based on how you already structured your code. No need for me to maintain a fork to be able to use it in a Gradle plugin.

[cypherdare]

The two follow-up commits:

• I realized this couldn't be used from Java without a package declared, in case anyone wants to use it in a Java project.
• I discovered you're supposed to use io.github rather than com.github as your prefix. details here