This commit is the result of a squash of all the commits created during
the development of libgpiod v2. This is done to preserve bisectability
of the git tree. It contains significant re-writes of the core C library
as well as C++ and python bindings. The tools have been adjusted to work
with the new API but have not undergone significant changes yet.

This commit contains the bulk of the work on libgpiod v2 but the
development continues with more changes planned.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
[Ben: fix format specifier for uint64_t]
Signed-off-by: Ben Hutchings <ben.hutchings@mind.be>
[Viresh: Fix ioctl number for gpiod_line_request_reconfigure_lines()]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
[Kent: bug fixes, improvements, better pointer contracts, type strictness]
Signed-off-by: Kent Gibson <warthog618@gmail.com>