'while4' prints 4th powers of integer numbers

Program terminates when it's not enough 4 digits to print out 4th power
of number. Shows using of while loop.
Use underscores in long numbers in Rust

Also, remove unnecessary parameter from D's writeln() in file endon0.d
'fibo' prints Fibonacci numbers

Program run until fibbonaci numbers fits in unsigned long (uint64) type.