In the lib, we should only #include "sigrok.h" or "sigrok-internal.h",
but not the (possibly installed and thus different/older versions) via
<sigrok.h> or <sigrok-internal.h>.
Frontends should of course use <sigrok.h> and <sigrok-internal.h>.
This is useful to allow frontends to react upon close failures in a
way they see fit (e.g. a popup in the GUI, or error message in the CLI).
They can also still ignore the error if they want, of course.
We should use these (internal) functions in libsigrok exclusively from
now on, i.e. no more use of glib's g_debug() etc.
These functions are only for libsigrok, the frontends use whatever
logging mechanism is suitable there.
* Both Analog and Logic capture works.
* Analog values are raw ADC, still useless.
* Triggers aren't implemented.
* Pattern Generator not implemented.
* Everything is broken. :)