Extract and display the total calories stored in file

[SamR1]

Some devices and applications record total calories in the generated files. This value can be extracted to be displayed on FitTrackee.

[!NOTE] Another issue exists regarding calories calculation: https://github.com/SamR1/FitTrackee/issues/6.

TODO:

• Extracts total calories from file and display it on Workout detail
• Add chart to display total calories in Statistics

Technical infos:

• .fit file: total_calories value is stored in session-type message
• .tcx file: calories are stored in <Calories> tag