Added the environment specification (it was suspiciously missing).

Fixed #4: Yup, you can use C++11 if you want. It's difficult to see what
you would need beyond auto for convenience though.

Fixed #5: I've given examples of compilers that may get used, depending
where I happen to be when I run it. Over-inclusion of headers I'm aware
of, and will fix during compilation. Usually I run it under two platforms
to check they are the same output, and to look for non-det bugs. Anything that is
genuinely a compiler or system bug, I'll just fix. If xcode doesn't
comply with the C/C++ standards then... don't use it.

Fixed #11: dup of 4.
Fixed #6 : ambiguity in mips_mem_free spec