Add @since tags to some (not all yet) public API functions, to document
in which release they were added (and/or in which release there were
API changes).
Document the @since usage in HACKING.
Also, add Doxygen docs for the functions in version.c.
This adds a suite of unit tests for libsigrok. It uses the 'Check'
tool/library (apt-get install check) to run the tests.
The configure tool tries to find libcheck. If it succeeds, a
"make check" will run all tests. Otherwise, none of the tests will
be built and "make check" will not run any tests.
This also means that users who don't have 'check' installed will still
be able to build and install libsigrok just fine.
Uwe Hermann