STK600 support

### Describe the request

The STK600 development board is fully compatible with the Arduino IDE

[https://github.com/zarpli/STK600](https://github.com/zarpli/STK600)

It would be very helpful if you add the following parameters in "programmers.txt" file:
```
stk600.name=Atmel STK600 development board
stk600.communication=usb
stk600.protocol=stk600
stk600.program.protocol=stk600
stk600.program.tool=avrdude
stk600.program.tool.default=avrdude
stk600.program.extra_params=
```

### Describe the current behavior

currently parameters must be entered on each new installation :(

Start with programmers.txt, which the issue identifies as the file requiring the change, and compare its existing programmer entries with the requested STK600 parameters. Done means the STK600 appears as an available programmer after a fresh Arduino IDE installation without manually entering these settings.

Written by the indexing model from the issue text.