* fix fstat wrong on darwin
* move std.debug.global_allocator to std.debug.global_allocator_state and make it private
* add std.debug.global_allocator as a pointer (to upgrade your zig code remove
the '&')
* Merge io.InStream and io.OutStream into io.File
* Introduce io.OutStream and io.InStream interfaces
- io.File implements both of these
* Move mem.IncrementingAllocator to heap.IncrementingAllocator
Instead of:
```
%return std.io.stderr.printf("hello\n");
```
now do:
```
std.debug.warn("hello\n");
```
To print to stdout, see `io.getStdOut()`.
* Rename std.ArrayList.resizeDown to std.ArrayList.shrink.
