Restructuring heat solver

Author: jussienko

interface/c/README.md

@@ -6,6 +6,6 @@ The files `evolve.h` and `evolve.c` contain a pure C implementation of the
 single time step in heat equation. The C implemention can be built into a
 shared library with the provided [Makefile](Makefile) by executing `make`
 command. Use **cffi** for utilizing the library function instead of the Python
-function in [heat_simple.py](heat_simple.py). Compare the performance to
-Cython implementation
+function in [heat.py](heat.py). Compare the performance to
+Cython implementation.