The sources can now conditionally compile emulation code
for the e-ink framebuffer and input events.
It uses SDL for doing that, so you need this installed
if you want to use emulation (you do not need it if you're
only compiling for the e-ink device).
This allows for rapid testing of new code.
usage in Lua:
dc:setGamma(1.5)
print(dc:getGamma())
set it to a negative value to disable gamma correction
(since gamma correction will always imply calculations
over the full buffer data).
