refactor: relative() renamed to quantity_from_origin()

Resolves #479

example/kalman_filter/kalman.h

@@ -212,7 +212,7 @@ struct MP_UNITS_STD_FMT::formatter<kalman::estimation<Q>> {
       if constexpr (mp_units::Quantity<Q>)
         return t;
       else
-        return t.relative();
+        return t.quantity_from_origin();
     }(kalman::get<0>(e.state));
 
     std::string value_buffer;

example/kalman_filter/kalman_filter-example_6.cpp

@@ -45,7 +45,7 @@ template<QuantityPoint QP, QuantityOf<dimensionless> K>
 void print(auto iteration, K gain, QP measured, kalman::estimation<QP> current, kalman::estimation<QP> next)
 {
   std::cout << MP_UNITS_STD_FMT::format("{:2} | {:7%.4Q} | {:10%.3Q %q} | {:>18.3} | {:>18.3}\n", iteration, gain,
-                                        measured.relative(), current, next);
+                                        measured.quantity_from_origin(), current, next);
 }
 
 int main()

example/kalman_filter/kalman_filter-example_7.cpp

@@ -45,7 +45,7 @@ template<QuantityPoint QP, QuantityOf<dimensionless> K>
 void print(auto iteration, K gain, QP measured, kalman::estimation<QP> current, kalman::estimation<QP> next)
 {
   std::cout << MP_UNITS_STD_FMT::format("{:2} | {:7%.4Q} | {:10%.3Q %q} | {:>18.3} | {:>18.3}\n", iteration, gain,
-                                        measured.relative(), current, next);
+                                        measured.quantity_from_origin(), current, next);
 }
 
 int main()

example/kalman_filter/kalman_filter-example_8.cpp

@@ -45,7 +45,7 @@ template<QuantityPoint QP, QuantityOf<dimensionless> K>
 void print(auto iteration, K gain, QP measured, kalman::estimation<QP> current, kalman::estimation<QP> next)
 {
   std::cout << MP_UNITS_STD_FMT::format("{:2} | {:7%.3Q} | {:10%.3Q %q} | {:>16.2} | {:>16.2}\n", iteration, gain,
-                                        measured.relative(), current, next);
+                                        measured.quantity_from_origin(), current, next);
 }
 
 int main()