Drop deprecated symbols

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>
Use symbol versioning

This isn't the final 0.8.0 API yet, but we might as well get started.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>
doc: include README as mainpage

doxygen supports markdown so we can expand the README with general interesting
information in markdown format and have it be the front page of the
documentation at the same time.

This requires renaming README to README.txt, but that's a relatively small
price to pay.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>
doc: add the various events to the doxygen groups

Makes them show up on the respective page and in the data structures list
doxygen generates.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>
doc: document the base structures so they show up in doxygen

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>
doc: put some extra warning in for libinput_event_destroy()

Unlike all other structs, events aren't refcounted and will get destroyed
immediately.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>