add device names as comments

we use mostly code names internally, but it is probably a good idea
to annotate the actual device names.
allow emulator to specify a viewport

This allows for Viewport debugging. It is configured via an environment
variable, EMULATE_READER_VIEWPORT. It works with Lua table syntax, e.g.:
EMULATE_READER_VIEWPORT="{x=10,w=550,y=5,h=790}"
update base, fetch framebuffer fixes
add debugging output for device initialisation
Merge pull request #1269 from hwhw/master

pull fixes in base, plus some emulator features