core: examples: consistency cleanups

core: examples: consistency cleanups

A collection of minor cleanups to make the examples more consistent and
ease the addition of more examples:
 - reformat Makefile.am to simplify adding more examples
 - add line offset to value output
 - remove commas from edge event output
 - replace while(1) with for (;;)
 - fix a typo in Makefile.am
 - fix an error handling goto in toggle_line_value.c

Signed-off-by: Kent Gibson <warthog618@gmail.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>