* `zig build --export [obj|lib|exe]` changed to `zig build_obj`,
`zig build_lib` and `zig build_exe` respectively.
* `--name` parameter is optional when it can be inferred from the
root source filename. closes#207
* `zig build` now looks for `build.zig` which interacts with
`std.build.Builder` to describe the targets, and then the zig
build system prints TODO: build these targets. See #204
* add `@bitcast` which is mainly used for pointer reinterpret
casting and make explicit casting not do pointer reinterpretation.
Closes#290
* fix debug info for byval parameters
* sort command line help options
* `std.debug.panic` supports format string printing
* add `std.mem.IncrementingAllocator`
* fix const ptr to a variable with data changing at runtime.
closes#289
* `@truncate` builtin allows casting to the same size integer.
It also performs two's complement casting between signed and
unsigned integers.
* The idiomatic way to convert between bytes and numbers is now
`mem.readInt` and `mem.writeInt` instead of an unsafe cast.
It works at compile time, is safer, and looks cleaner.
* Implicitly casting an array to a slice is allowed only if the
slice is const.
* Constant pointer values know if their memory is from a compile-
time constant value or a compile-time variable.
* Cast from [N]u8 to []T no longer allowed, but [N]u8 to []const T
still allowed.
* Fix inability to pass a mutable pointer to comptime variable at
compile-time to a function and have the function modify the
memory pointed to by the pointer.
* Add the `comptime T: type` parameter back to mem.eql. Prevents
accidentally creating instantiations for arrays.
Andrew Kelley