Remove legacy JVM-specific file system, shell, and related implementations; migrate to platform-agnostic and common main modules.

src/commonMain/kotlin/mtmc/os/shell/builtins/SpeedCommand.kt

@@ -0,0 +1,38 @@
+package mtmc.os.shell.builtins
+
+import mtmc.emulator.MonTanaMiniComputer
+import mtmc.os.shell.ShellCommand
+import mtmc.tokenizer.MTMCToken
+import mtmc.tokenizer.MTMCTokenizer
+
+class SpeedCommand : ShellCommand() {
+  private val speeds = listOf(
+      1, 10, 100, 1000, 10000, 100000, 1000000
+  )
+
+  @Throws(Exception::class)
+  override fun exec(tokens: MTMCTokenizer, computer: MonTanaMiniComputer) {
+    if (tokens.match(MTMCToken.TokenType.IDENTIFIER)) {
+      computer.speed = 0
+    } else if (tokens.match(MTMCToken.TokenType.INTEGER)) {
+      val speed = tokens.consumeAsInteger()
+      if (!speeds.contains(speed)) {
+        usageException()
+      }
+      computer.speed = speed
+    } else {
+      usageException()
+    }
+  }
+
+  override val help: String
+    get() = """
+speed <val> - set the speed of the computer
+  where <val> is one of:
+     raw  - run with no simulated speed delay
+     1    - run the computer at 1hz
+     10   - run the computer at 10hz
+     100  - run the computer at 100hz
+     1000 - run the computer at 1khz
+     """.trimIndent()
+}