Complete transition to fn. Introduce global/threadlocal

test/test_suite/assert/assert_variants.c3t

@@ -1,11 +1,11 @@
 // #target: x64-windows
 
-func int foo()
+fn int foo()
 {
     return 1;
 }
 
-func void test()
+fn void test()
 {
     int x = foo();
     int y = foo();

test/test_suite/assert/local_static_assert_not_constant.c3

@@ -1,19 +1,19 @@
 int x = 3;
 
-func void test()
+fn void test()
 {
     $assert(x == 3); // #error: Compile time evaluation requires a compile time constant value.
 }
 
-func void test2()
+fn void test2()
 {
     int i = 0;
     $assert(1);
     $assert(i == 0); // #error: Compile time evaluation requires a compile time constant value.
 }
 
-func int foo();
-func void test3()
+fn int foo();
+fn void test3()
 {
     int i = 0;
     $assert(foo() == 0); // #error: Compile time evaluation requires a compile time constant value.

test/test_suite/assert/static_assert.c3

@@ -1,7 +1,7 @@
 
 const int FOO = 2;
 
-func void test()
+fn void test()
 {
     $assert(FOO == 2, "Bad");
     $assert(FOO == 0, "Good"); // #error: Compile time assert - Good

test/test_suite/assert/unreachable.c3t

@@ -1,10 +1,10 @@
 
-func int foo()
+fn int foo()
 {
     return 1;
 }
 
-func void test()
+fn void test()
 {
     int x = foo();
     if (x > 0) return;