use * for pointer type instead of &

See #770

To help automatically translate code, see the
zig-fmt-pointer-reform-2 branch.

This will convert all & into *. Due to the syntax
ambiguity (which is why we are making this change),
even address-of & will turn into *, so you'll have
to manually fix thes instances. You will be guaranteed
to get compile errors for them - expected 'type', found 'foo'

std/zig/parser_test.zig

@@ -1803,7 +1803,7 @@ const io = std.io;
 
 var fixed_buffer_mem: [100 * 1024]u8 = undefined;
 
-fn testParse(source: []const u8, allocator: &mem.Allocator, anything_changed: &bool) ![]u8 {
+fn testParse(source: []const u8, allocator: *mem.Allocator, anything_changed: *bool) ![]u8 {
     var stderr_file = try io.getStdErr();
     var stderr = &io.FileOutStream.init(&stderr_file).stream;