Refactor source layout

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

[no changelog]

src/main/kotlin/util/assertions.kt

@@ -0,0 +1,25 @@
+
+
+package moe.nea.firmament.util
+
+/**
+ * Less aggressive version of `require(obj != null)`, which fails in devenv but continues at runtime.
+ */
+inline fun <T : Any> assertNotNullOr(obj: T?, message: String? = null, block: () -> T): T {
+    if (message == null)
+        assert(obj != null)
+    else
+        assert(obj != null) { message }
+    return obj ?: block()
+}
+
+
+/**
+ * Less aggressive version of `require(condition)`, which fails in devenv but continues at runtime.
+ */
+inline fun assertTrueOr(condition: Boolean, block: () -> Unit) {
+    assert(condition)
+    if (!condition) block()
+}
+
+