can't create a time series unles user selects at least two times [1246]
Obey user's side legend preference.
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
Only pop up user message if running in foreground [1246]
Use the most appropriate method to alert user [1246]
Merge pull request #42 from tommyjasmin/master

Make sure user selects at least two times before going ahead with creating Time Series Chart.

Tommy, Bob and I have gone round and round on this and it looks good.
Merge pull request #43 from jon4than/sidelegend_pref_fix

Obey user's side legend preference.