Better support for Negative, Inf, NaN and High Values

Some ride file formats use -1 to indicate sensor not
present or data loss (e.g. TPX) and on occasion a NaN
or Infinite value will be presented.

This patch handles this by converting negative data sample
values to zero and handling out of bounds values when
selecting zone ranges.

This is not a substitute for better handling of poor ride
data but it reduces the effect.

Also fixes #311.

src/HrZones.cpp

@@ -440,7 +440,10 @@ int HrZones::whichZone(int rnum, double value) const
         if ((value >= info.lo) && (value < info.hi))
             return j;
     }
-    return -1;
+
+    // if we got here either it is negative, nan, inf or way high
+    if (value < 0 || isnan(value)) return 0;
+    else return range.zones.size()-1;
 }
 
 void HrZones::zoneInfo(int rnum, int znum,

src/RideFile.cpp

@@ -287,6 +287,17 @@ void RideFile::appendPoint(double secs, double cad, double hr, double km,
                            double kph, double nm, double watts, double alt,
                            double lon, double lat, double headwind, int interval)
 {
+    // negative values are not good, make them zero
+    // although alt, lat, lon, headwind can be negative of course!
+    if (secs<0) secs=0;
+    if (cad<0) cad=0;
+    if (hr<0) hr=0;
+    if (km<0) km=0;
+    if (kph<0) kph=0;
+    if (nm<0) nm=0;
+    if (watts<0) watts=0;
+    if (interval<0) interval=0;
+
     dataPoints_.append(new RideFilePoint(secs, cad, hr, km, kph,
                                          nm, watts, alt, lon, lat, headwind, interval));
     dataPresent.secs  |= (secs != 0);

src/Zones.cpp

@@ -437,7 +437,10 @@ int Zones::whichZone(int rnum, double value) const
         if ((value >= info.lo) && (value < info.hi))
             return j;
     }
-    return -1;
+
+    // if we got here either it is negative, nan, inf or way high
+    if (value < 0 || isnan(value)) return 0;
+    else return range.zones.size()-1;
 }
 
 void Zones::zoneInfo(int rnum, int znum,