Fix Nuclide Decay Info tool showing all nuclides as stable.

This bug was introduced when "internationalizing" the app.
Closes #39.

Author: wcjohns

InterSpec_resources/app_text/InterSpec.xml

@@ -81,6 +81,7 @@
   <message id="Unknown">Unknown</message>
   <message id="Energy (keV)">Energy (keV)</message>
   <message id="Efficiency">Efficiency</message>
+  <message id="stable">stable</message>
 
   <!-- Units the user may use to write time duration.
     Note that we dont have very good changing case (i.e., from lower to upper, or upper to lower)

src/DecayChainChart.cpp

@@ -469,7 +469,9 @@ void DecayChainChart::jsonInfoForNuclide( const SandiaDecay::Nuclide * const nuc
 
   vector<string> info = getTextInfoForNuclide( nuc, m_nuclide, m_useCurie );
 
-  const string hl = (IsInf(nuc->halfLife) ? std::string("stable") : PhysicalUnitsLocalized::printToBestTimeUnits(nuc->halfLife, 2));
+  
+  const string hl = IsInf(nuc->halfLife) ? WString::tr("stable").toUTF8()
+                                          : PhysicalUnitsLocalized::printToBestTimeUnits(nuc->halfLife, 2);
 
   js << "{ \"nuclide\": \"" << nuc->symbol << "\","
     << " \"massNumber\": " << static_cast<int>(nuc->massNumber) << ","
@@ -597,7 +599,7 @@ std::vector<std::string> DecayChainChart::getTextInfoForNuclide( const SandiaDec
   }else
   {
     const string hl = PhysicalUnitsLocalized::printToBestTimeUnits( nuc->halfLife );
-    information.push_back( WString::tr("dcc-nuc-info-hl-stable").arg(hl).toUTF8() );
+    information.push_back( WString::tr("dcc-nuc-info-hl").arg(hl).toUTF8() );
   }
 
   if( parentNuclide && (nuc != parentNuclide) )