Reverted to ecmd setting target temp.

"heating 200" will sett the target temp to 20.0 degC
Now gdb debugging of CU_test1.c works

It seems the -g parameter was in the wrong place before. Moved it to
CFLAGS.
Adding printf_P to the stubs

Also fixed some indentation.
Merge branch 'gdb_test' into heating_ctrl_w_test
Really gettins somewhere with CUnit

Now the debugging works. 
Finished a test of filter_ewma.
Expanding the PI-controller test.