[EPD] special border code for 1.44" EPD

1. border byte at start of each line
2. special border dummy line at end of frame

Signed-off-by: Christopher Hall <christopherhall.hsw@gmail.com>
[demo] easier image selection / no initial size set

some tricky pre-processor macros so the two images can be set by lines
a simply as:

Set the SCREEN_SIZE macro initially zero so first time compile fails
rather than building for the wrong display size.

Signed-off-by: Christopher Hall <christopherhall.hsw@gmail.com>