Dwgdbserver

- Changed: power_cycle is now a method.

- Apparently, one should not request a reset after connecting. Removing that helped a lot. Well, turned out later that this was a symptom of not restarting the housekeeping session (see V0.9.5).
- MCUs with Stuck-at-1-bits are identified.
- Added code to honor the fact that the ATmega88/168/328 pretend to be P-versions when in debugWIRE mode
- Set the EEARH field in the activation record to EEARL+1. This seems to be the right choice when following the datasheet for the ATmega48. And it led to success in starting the MCU.

- Works now with ATmega328P
- harvested all debugWIRE MCUs with the new script dw-harvest.py
- does not work with ATmega48, and probably not with others ...

- basic functionality for using it as a gdbserver is implemented
- if already in debugWIRE mode, debugging is started right after `target remote`
- suppressed some spurious error messages from `nvmspi` and `jtagice3protocol` by setting the log level to `CRITICAL` for these modules
- set `pyedglib` log level to `INFO` when general level is `DEBUG`

- `monitor debugwire on` now first tries ISP and will ask for power-cycle
- if ISP does not work, we switch directly DW on
- `monitor debugwire off` only works once, but this is OK!
- the device parameter is now tested against DW and ISP targets
- multiple NAKs caused by time-outs waiting for power-cycling are bulk deleted
- implemented a callback function when calling `dbg.setup_session` for notifying in the debug console that a power-cycle is necessary
- Added `dwe_nvmspi.py` in order to suppress the warning message in the initial method

- check first on whether there are potential debuggers at all and if not, we start dw-link immediately
- checked for each command that dw_mode is active; if not an error reply is given
- added field `dwen_fuse` to the device description for debugWIRE devices (its always in the high fuse)
- in avrdebug.py, put part of `setup_session` into `__init__` so that device and memory infos are available before connecting to the device