revisit the RSSI implementation

This changes the behaviour to make a clear difference between RSSI
and link quality.

Composite RSSI now shows RSSI when linkquality is perfect as output
values of 80-100%.

If quality is degraded the composite output will switch to pure
quality as 0-75%.

Thus it is possible to ignore RSSI by setting 'max' to 80%.
astyle run
Makefile stuff