Fix precision loss on consumed_energy.csv

[JRodez]

Fix precision loss in consumed_energy.csv
Formatting with C99 "%g" cuts by 2 the precision of doubles, which is used to store dates.
Now "%lf" is used instead, which is the standard format for doubles.

Checklist

Branch name.

• Descriptive and short
• Use hyphens to separate words

Branch content.

• Only dedicated to the problem.
• Based on Batsim's official master branch.
• Straightforward. Just a sequence of commits. Does not contain merge commits.
• Test results are not worse than before. How to run Batsim tests?

[mpoquet]

Thanks! Merged in f225198.