Added vdottime(VDOT, distance) to formulas

Computes the equivalent time (in seconds) for distance (in km)
at VDOT, tipically used with VDOT metric as first parameter.

src/DataFilter.cpp

@@ -23,6 +23,7 @@
 #include "RideNavigator.h"
 #include "RideFileCache.h"
 #include "PMCData.h"
+#include "VDOTCalculator.h"
 #include <QDebug>
 
 #include "Zones.h"
@@ -95,6 +96,9 @@ static struct {
     { "unset", 2 }, // unset(symbol, filter)
     { "isset", 1 }, // isset(symbol) - is the metric or metadata overridden/defined
 
+    // VDOT functions
+    { "vdottime", 2 }, // vdottime(VDOT, distance[km]) - result is seconds
+
     // add new ones above this line
     { "", -1 }
 };
@@ -1951,6 +1955,15 @@ Result Leaf::eval(Context *context, DataFilter *df, Leaf *leaf, float x, RideIte
                 }
                 break;
 
+        case 35 :
+                {   // VDOTTIME (VDOT, distance[km])
+
+                    if (leaf->fparms.count() != 2) return Result(0);
+
+                    return Result (60*VDOTCalculator::eqvTime(eval(context, df, leaf->fparms[0], x, m, p).number, 1000*eval(context, df, leaf->fparms[1], x, m, p).number));
+                }
+                break;
+
         default:
             return Result(0);
         }