update firmware.bin
Merge pull request #516 from wolfmanjm/upstreamedge

cap zprobe retract rate to zprobe fast feedrate
only use 5th line in zprobe status if screen has more than 4 lines
add viki2 and miniviki2 panels
allow configure menu items to be set as the encoder turns (be careful with use)
add set lcd contrast to Configure menu (needs to be set permanently in config)
add buzz and red/blue leds for viki2 panel
add example coinfig for viki2
add a LED_HOT that gets set if the temp of hotend or bed is > 50C
viki2 set red led if hot blue led if not
specify variant in ctor
add mini_viki2 as it needs different contrast and encoder resolution
fix opendir bug for multiple FAT volumes
Add sd card insertion detection and mount exernal sd
fix a bug in readdir that casued stack overrun (fixed in upstream mbed already)
move extern sdcard detect to panel
allow configure of where extern sdcard is plugged in
when extern sdcard is inserted jump to that directory in play screen
switch SDCard to use mbed::SPI as it remembers the frequency to use for each device
fix white space changes
update pins for viki2 on an azteeg X5 mini V2
Merge pull request #517 from wolfmanjm/add/viki2

Add/viki2
Merge pull request #518 from wolfmanjm/add/external-sdcard

Add/external sdcard
fix race when external card is already inserted