feat: replace IO class with System class and remove separate IO module

- Delete wren_io.c, wren_io.h, and io.wren source files
- Remove multi-arity print overloads and IO.read/IO.time methods
- Add System class with print, printAll, write, writeAll methods to core.wren
- Update all documentation examples and README to use System.print instead of IO.print

test/language/logical_operator/and.wren

@@ -1,20 +1,20 @@
 // Note: These tests implicitly depend on ints being truthy.
-//       Also rely on IO.print() returning its argument.
+//       Also rely on System.print() returning its argument.
 
 // Return the first non-true argument.
-IO.print(false && 1) // expect: false
-IO.print(true && 1) // expect: 1
-IO.print(1 && 2 && false) // expect: false
+System.print(false && 1) // expect: false
+System.print(true && 1) // expect: 1
+System.print(1 && 2 && false) // expect: false
 
 // Return the last argument if all are true.
-IO.print(1 && true) // expect: true
-IO.print(1 && 2 && 3) // expect: 3
+System.print(1 && true) // expect: true
+System.print(1 && 2 && 3) // expect: 3
 
 // Short-circuit at the first false argument.
-IO.print(true) && // expect: true
-    IO.print(false) && // expect: false
-    IO.print(false) // should not print
+System.print(true) && // expect: true
+    System.print(false) && // expect: false
+    System.print(false) // should not print
 
 // Swallow a trailing newline.
-IO.print(true &&
+System.print(true &&
     true) // expect: true

test/language/logical_operator/and_truth.wren

@@ -1,8 +1,8 @@
 // False and null are false.
-IO.print(false && "bad") // expect: false
-IO.print(null && "bad") // expect: null
+System.print(false && "bad") // expect: false
+System.print(null && "bad") // expect: null
 
 // Everything else is true.
-IO.print(true && "ok") // expect: ok
-IO.print(0 && "ok") // expect: ok
-IO.print("" && "ok") // expect: ok
+System.print(true && "ok") // expect: ok
+System.print(0 && "ok") // expect: ok
+System.print("" && "ok") // expect: ok

test/language/logical_operator/or.wren

@@ -1,20 +1,20 @@
 // Note: These tests implicitly depend on ints being truthy.
-//       Also rely on IO.print() returning its argument.
+//       Also rely on System.print() returning its argument.
 
 // Return the first true argument.
-IO.print(1 || true) // expect: 1
-IO.print(false || 1) // expect: 1
-IO.print(false || false || true) // expect: true
+System.print(1 || true) // expect: 1
+System.print(false || 1) // expect: 1
+System.print(false || false || true) // expect: true
 
 // Return the last argument if all are false.
-IO.print(false || false) // expect: false
-IO.print(false || false || false) // expect: false
+System.print(false || false) // expect: false
+System.print(false || false || false) // expect: false
 
 // Short-circuit at the first true argument.
-IO.print(false) || // expect: false
-    IO.print(true) || // expect: true
-    IO.print(true) // should not print
+System.print(false) || // expect: false
+    System.print(true) || // expect: true
+    System.print(true) // should not print
 
 // Swallow a trailing newline.
-IO.print(true ||
+System.print(true ||
     true) // expect: true

test/language/logical_operator/or_truth.wren

@@ -1,8 +1,8 @@
 // False and null are false.
-IO.print(false || "ok") // expect: ok
-IO.print(null || "ok") // expect: ok
+System.print(false || "ok") // expect: ok
+System.print(null || "ok") // expect: ok
 
 // Everything else is true.
-IO.print(true || "ok") // expect: true
-IO.print(0 || "ok") // expect: 0
-IO.print("s" || "ok") // expect: s
+System.print(true || "ok") // expect: true
+System.print(0 || "ok") // expect: 0
+System.print("s" || "ok") // expect: s