Refactering the FISTA & IGD Python code
Refactoring FISTA & IGD C++ code
Improvement on the preformance of FISTA

* Use an adaptively changing stepsize, which is allowed to increase with
  a probability. This minimizes the performance dependence on
  max_stepsize.

* Use a smaller eta, to explore the stepsize more closely

These two decrease the running time for cvtest1 data set from 140s to
40s.
C++ coding is done
Coding for elastic net logistic models almost completed
Fixing bugs.

Logistic results are wrong. There are more bugs.