incorrect free memory

[Yingtian Liu]

Putting multiple array pointers in a single delete[] line is incorrect. E.g., in base_solver.h:

Fast-Poisson-Image-Editing/fpie/core/base_solver.h

Line 28 in 6a607f1

 delete[] A, B, X; 

and

Fast-Poisson-Image-Editing/fpie/core/base_solver.h

Line 98 in 6a607f1

 delete[] mask, tgt, grad; 

They lead to memory leaks.

Instead, they should be

    delete[]  A;
    delete[]  B;
    delete[]  X;

and

    delete[]  mask;
    delete[]  tgt;
    delete[]  grad;