* Wrap >4-char literals in a MULTI_CHAR macro
Modern compilers do not support CW's non-standard behavior with
>4 char literals. We can, however, use a constexpr function to
compute the u64 values directly. This leaves <=4 char literals
unchanged.
* Replace non-pointer usages of NULL with 0
* Define NULL to nullptr on C++11 and above
* Fix more -Wpointer-arith and -Woverflow warnings
* Replace u32/s32 with uintptr_t/intptr_t where appropriate
* JSUOutputStream: Overload all standard int types
Luke Street