dev

1.fixed a big bug in the proof, fortunately, the fundamental result does not need to change
2. to observer the performance of the long-range link, I can first measure the one on a completed overlay network, leaving the dynamism to a little later
the function void fling() is defined in overlay network class

3. gnu multiprecision does not provide efficient logarithmic or exponential function, and the output function is also inflexible, based on FILE structure