Refactor: Restructure project package hierarchy and add initial implementation for assembler instructions, shell commands, and exception handling.

src/jvmMain/kotlin/mtmc/emulator/MTMCIO.kt

@@ -0,0 +1,28 @@
+package mtmc.emulator
+
+import java.util.*
+
+class MTMCIO {
+  var value: Int = 0
+
+  internal enum class Buttons(val mask: Int) {
+    UP(128),
+    DOWN(64),
+    LEFT(32),
+    RIGHT(16),
+    START(8),
+    SELECT(4),
+    B(2),
+    A(1)
+  }
+
+  fun keyPressed(key: String) {
+    val button = Buttons.valueOf(key.uppercase(Locale.getDefault()))
+    value = value or button.mask
+  }
+
+  fun keyReleased(key: String) {
+    val button = Buttons.valueOf(key.uppercase(Locale.getDefault()))
+    value = value and button.mask.inv()
+  }
+}