[fix] add dev headers to _SOURCES

See merge request !14

Track development headers in src/Makefile.am _SOURCES to make sure that
`make dist` will include them in the distribution.

Might also fix some errors when modifying a header and recompiling.

See https://www.gnu.org/software/automake/manual/html_node/Headers.html
for the guidelines.

[tests] add rule to build tests w/o running them

See merge request !13

Production systems might sometimes require that we build the check
programs on a different machine that the one we run them. This
additional rule allows us to trigger building the programs without
triggering the run.

[fix] Adds Kamil in AUTHORS

See merge request !12

Improve English in the comments of the main header

See merge request !11

Also do some minor tweaking of const.

[ci] Adding CI, fixing authors, license.

See merge request !10

Index

See merge request !8

Tleaf

See merge request !6