Fix android method call

[martin308]

Discovered by @willispinaud in #88, the way we were calling this method fails on android v6. Dropping back down to the lower level JNI calls resolves this.

Have tested this on android 4, 5 and 6 on a device.

[fractalwrench]

Would it be possible to get an explanation of what the issue was on Android? Is this an issue on later devices e.g. Android 7, 8?

[martin308]

It wasn't entirely obvious what the issue was. My biggest hunch is that it couldn't infer which method to call based on the arguments provided anymore. Although I'm not sure how this relates to just the android version changing. I'm currently working on getting unity android maze-runner tests running so that I can test on other versions

[fractalwrench]

Adding new tests that cover this functionality, and running them on all API levels sounds like a good start. I think it'd also be worth spending a bit of time trying to understand why the original code was causing a crash, as it may reveal that the fix doesn't work for all inputs, or that similar issues exist elsewhere in our use of the JNI.