Fixed a bug in the boot unpickler on Windows and (possibly) Mac OS.

The file stream of the input was not opened in binary mode, hence
eof characters and (maybe?) carriage returns were "interpreted"!
Added an overload of toUTF() for wchar_t.
Downgraded max memory of the emulator to 768 MB.

This allows the emulator to be run on Windows with the 32-bit limit.
Fixed bug about file paths on Windows.

Now /'s in file paths are automatically converted to \'s by OS.fopen.
Tiny comment cleanup in VM::run().
Added correct implementation of System.printName.
Removed the opcode deallocateY.

Now return, tailCall and tailSendMsg take care themselves of
freeing the Y register.