Remove unused code from flexmeasures.js

[nhoening]

In ui.static.js.flexmeasures.js, we have lots of code about the general behavior of the FlexMeasures UI.

We also have specific code, e.g. for the control page (lines 212 to 287 as of now) or the analytics page (at the bottom). These should be deleted (after some consideration). Everything with "control" in the name might be suspect of being unused.

I believe that our UI tests are not really testing whether JavaScript loads correctly, so some manual testing would be good afterward.

[nhoening]

Also, some code is not needed at the moment, as we changed what pages are being used (i.e. analytics is out). This issue should do the cleanup there, or comment the loading of that code out.