Merge branch 'feature/r0_fix' into 'master'

Handled reproduction number error, and added close X button

See merge request cara/cara!373

cara/apps/templates/base/calculator.form.html.j2

@@ -391,6 +391,9 @@
         <div class="modal-content">
           <div class="modal-header">
             <h5 class="modal-title" id="short_range_dialogTitle">Short-range interactions</h5>
+            <button type="button" class="close close_btn_frm_field">
+              <span aria-hidden="true">&times;</span>
+            </button>
           </div>
           <div class="modal-body">
 

cara/models.py

@@ -1422,7 +1422,13 @@ class ExposureModel:
                 self.concentration_model.virus.transmissibility_factor)))) * 100
 
     def expected_new_cases(self) -> _VectorisedFloat:
-        prob = self.infection_probability()
+        # Create an equivalent exposure model without short-range interactions, if any.
+        if (len(self.short_range) == 0): 
+            exposure_model = nested_replace(self, {'short_range': ()})
+            prob = exposure_model.infection_probability()
+        else:
+            prob = self.infection_probability()
+            
         exposed_occupants = self.exposed.number
         return prob * exposed_occupants / 100