Fix speed display in energy graph

I will admit that the idiotic number versus string confusion in javascript
really drives me angry. I am now trying to go out of my way to avoid
implicit conversions by making them explicit and hoping that the variables
don't suddenly change type on me again.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Only load new page if date range is non-empty

There is no point to loading a new page if from is after to, so let's just
not do it.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Draw points as well as lines for average consumption

Otherwise in single day mode you can't see the value.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Add tooltip to SOC chart

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Add cumulative energy used / regen to energy chart

This shows is the explanation below the graph how much energy was spent
and how much energy was regenerated. Seems like interesting data to me.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
More integer vs. string confusion

This caused the map application to occasionally draw lines to and from GPS
(0,0) (the ocean West of central Africa). Oops.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Merge pull request #31 from dirkhh/moreFixes

More fixes