Added transition points to dilution factor methods// Added emission rate comparison

Reviewed added just to be aware of the changes in the dilution_factor method:

label, color and marker to be adapted.

Added emission rate comparison method for different physical activities: short_range_emission_rate_physical_activity_comparison:

Expiratory Activity: Speaking 
First Physical Activity:  Heavy exercise 
Second Physical Activity:  Standing 
vR_sr_1 (first activity):  18901.06074067596 
vR_sr_2 (second activity):  3765.0490203124386 
vR_sr_1 / vR_sr_2 (Speaking): 5 -fold
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