GNU Astronomy Utilities: After making changes

GNU Astronomy Utilities

This is a checklist of things to do after applying your changes/additions in Gnuastro:

If the change is non-trivial, write test(s) in the tests/progname/ directory to test the change(s)/addition(s) you have made. Then add their file names to tests/Makefile.am.
Run $ make check to make sure everything is working correctly.
Make sure the documentation (this book) is completely up to date with your changes, see Documentation.
Commit your change to your issue branch (see Production workflow and Forking tutorial) Afterwards, run Autoreconf to generate the appropriate version number:
```
$ autoreconf -f
```
Finally, to make sure everything will be built, installed and checked correctly run
```
$ make distcheck
```
This command will create a distribution file (ending with .tar.gz) and try to compile it in the most general cases, then it will run the tests on what it has built in its own mini-environment. If $ make distcheck finishes successfully, then you are safe to send your changes to us to implement or for your own purposes. See Production workflow and Forking tutorial.