split -w option into -w WAVEFORM and -W

In order to remove the ambiguity around the -w option with a
non-required argument, -w now requires an argument (waveform
path) and -W is used to print the list of available waveforms.

Update the help message accordingly.

Signed-off-by: Guillaume Tucker <guillaume.tucker@plasticlogic.com>
Android.mk: add static libraries libplutil and libeglib
remove log.h and use plsdk/log.h instead
add -O option for config file path

Add -O option to specify an alternative configuration file
path.  Check whether the file is valid and abort if not.

Signed-off-by: Guillaume Tucker <guillaume.tucker@plasticlogic.com>
do not reset CFA and rotation when no user provided values

If the user didn't use the -r or -f options, do not reset the
rotation and CFA values to 0 as they may now be set to something
else from the config file.  This relies on the fact that -1 is
not a valid angle or CFA identifier.

Also fix auto rotation angle in plpng.c to take into account the
initial pldraw rotation value, which may have been loaded from
the configuration file.  If it was 180 or 270, show the image
rotated by 180 degrees (and still use match landscape/portrait
orientation between display and document).

+ add comments in epdoc.h about epdoc_opt options
Android.mk: add path to libplutil
ChangeLog v1.8 -> v1.9