Removes trailing whitespaces at end of lines

Unnecessary end of line whitespace is generally frowned upon. In addition some
editors remove end of line whitespace automatically, making diffs hard to read.
This commit removes all trailing witespaces. Using some sed magic in bash:

find . -name "*.*" -type f -print0 | xargs gsed -i 's/[ \t]*$//'

src/mlpack/core/kernels/epanechnikov_kernel.cpp

@@ -32,7 +32,7 @@ double EpanechnikovKernel::Evaluate(const double distance) const
 }
 
 /**
- * Evaluate gradient of the kernel not for two points 
+ * Evaluate gradient of the kernel not for two points
  * but for a numerical value.
  */
 double EpanechnikovKernel::Gradient(const double distance) const {