Write AVR fuses slowly

DUDE_SPEED is optimized for max speed and may fail
if the clock source is set to the slow internal
RC clock generator
Merge branch 'master' of https://github.com/fachat/XD2031
Fix broken SD-card support for XS-1541 w/ m1284p
Make XS-1541 AVR fuses settings depend on the selected MCU
Make avrdude more quiet, enable verbose output with make <target> V=1