Be strict about parsing errors

If a line isn't the input we need, complain and fail.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Skip over empty input lines

An empty input line should not case a parsing error, they can be silently
ignored.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
test: add test for reading in a device description

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
test: test for end-of-line comments

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
test: ensure we ignore events in description files

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
test: factor out a bit, make room for invalid file format checks

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
test: add test for empty lines

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
test: add tests for invalid file formats

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>