coreserver: Add range selection for insn state dump

Signed-off-by: Michael Buesch <m@bues.ch>
Port GUI to coreserver-API

Signed-off-by: Michael Buesch <m@bues.ch>
gui: Handle server messages with timeout

Signed-off-by: Michael Buesch <m@bues.ch>
gui: Only dump visible instructions

Signed-off-by: Michael Buesch <m@bues.ch>