There are different kinds of files in this directory:
- compare_fits is a program that can be used to compare FITS files, to verify
  that an algorithm always computes the same thing for example
- sorting is a unit test on the three sorting implementations that provide the
  median. It also contains a performance evaluation between them.

Other files are used for the build of these executables. Since they depend on
siril's code and we don't want to pull all the files here, we had to redefine
the functions used in the direct dependencies in dummy.c, they should not be
used in the tests.

To compile the test programs, compile siril then run ./build.sh.
Since sorting makes some performance tests, siril has to be compiled with -O2
to have real use values.

If build error occurs, check that the basic build script has all required
package links for your OS and options for your compiler.
If link error occurs, add the missing functions in dummy.c
