better documentation of number conversion function

src/boost-utils.h

@@ -12,9 +12,14 @@ fs::path boostfs_uncomplete(fs::path const p, fs::path const base);
 #include <boost/cast.hpp>
 #include <sstream>
 
-// convert number types (for example double to int) but print WARNING
-// for failures during conversion. >0 Overflow: return max of Tout,
-// <0 overflow return min, otherwise return 0. use std::numeric_limits
+/* Convert number types (for example double to int) but print WARNING
+ for failures during conversion. This is useful for situations where it
+ is important to not fail silently during casting or conversion. (For 
+ example, accidentally converting 64 bit types to 32 bit types, float to
+ int, etc).   
+ For positive overflow, return max of Tout template type
+ For negative overflow, return min of Tout template type
+ On other failures, return 0. */
 template <class Tout,class Tin> Tout boost_numeric_cast( Tin input )
 {
 	Tout result = 0;