Add API stubs to enumerate and create clock related objects
Partially unstub newly added API

Device enumeration now relies exclusively on `udev` API.
Populate `ambit_device_info_t` fields using `udev` API
Attempt to fill in fields with firmware information

Firmware name and serial number are preferred over `udev` information
if different.  Failure to get firmware information is *not* fatal when
populating of device info fields.
Unstub `libambit_new()`
Unstub `libambit_new_from_devname()`
Unstub `libambit_new_from_syspath()`
Reimplement GUI device detection with new API
Display access error message rather than support status

If we could not access the device, there is no knowing whether the
clock is supported.  Users need to address the access error first.
Make example application use new libambit API

Device information, access issues and support status are logged to
standard output before anything else.
Drop old device detection API
Drop obsoleted `libambit` API
Drop obsoleted `ambit_object_t` fields
Merge branch 'master' into device-detection

Conflicts (resolved in favour of 'device-detection' branch):
	src/example/ambitconsole.c
Fix one-off in known device detection logic.  Re #59
Remove editor droppings that accidently got into 714ce5b
Provide HID API based alternative implementation for device detection

This addresses a review comment on #62 about the `udev` dependency in
the face of portability.  The original `udev` implementation has been
kept for the time being so we can evaluate what is best.  The default
build will use the HID API version.
Remove devpath/syspath API in favour of a unified pathname API

The devpath/syspath API was arguably a `udev` thing.  The pathname
API is independent of whatever detection scheme is employed.

Re #62.
Drop `udev` device detection in favour of a `hidapi` one.  Re #59
Explicitly inline readability convenience function `is_hidraw()`

It no longer really improves code readability.

Re #59