Many things, most notable the lm78 module
* Some Makefile changes. doc/makefiles documents most of them.
* The lm78 module now compiles, but it will still crash.
* New module sensors, with general code usable by chip driver modules
* i2c-core: added function i2c_adapter_id(), which returns a (low)
unique i2c-bus ID.
* lm78.h stuff moved into lm78.c or sensors.h