FIX: remove input images list number check (input image can be one big stack)

app/otbTimeSeriesIndexTrend.cxx

@@ -290,10 +290,6 @@ private:
 
     // Get the NDVI time series input image list
     FloatVectorImageListType::Pointer inNDVIList = this->GetParameterImageList("ndvits");
-    if( inNDVIList->Size() < 2 )
-      {
-      otbAppLogFATAL("At least two NDVI images are required.");
-      }
 
     // Create one stack for input NDVI images list
     m_NDVIConcatener = ListConcatenerFilterType::New();
@@ -390,10 +386,6 @@ private:
 
         // Get the rainfall time series input images list
         FloatVectorImageListType::Pointer inRFList = this->GetParameterImageList("rainfts");
-        if( inRFList->Size() < 2 )
-          {
-            otbAppLogFATAL("At least two rainfall images are required.");
-          }
 
         // Create one stack for input RF images list
         m_RFConcatener = ListConcatenerFilterType::New();