tmc: colored output for temperature graph
tmc: colored output for temperature graph

- last 12h ours of temperatures will always be printed as graph on start
- graph lines will be printed if temperature has changed by at least on
  degree celsius
- fix: do not freak out when there is no connection to the server which
  hosts the tm_720.csv

poinck/tm,poinck/tm,poinck/tm,poinck/tm,poinck/tm