Refactor source layout

Introduce compat source sets and move all kotlin sources to the main directory

[no changelog]

src/main/kotlin/util/ErrorBoundary.kt

@@ -0,0 +1,10 @@
+
+
+package moe.nea.firmament.util
+
+
+fun <T> errorBoundary(block: () -> T): T? {
+    // TODO: implement a proper error boundary here to avoid crashing minecraft code
+    return block()
+}
+