removed base_prefix_family from unit classes, added PrefixFamily template argument to alias_unit

src/include/units/physical/si/area.h

@@ -52,7 +52,7 @@ struct square_exametre : deduced_unit<square_exametre, dim_area, exametre> {};
 struct square_zettametre : deduced_unit<square_zettametre, dim_area, zettametre> {};
 struct square_yottametre : deduced_unit<square_yottametre, dim_area, yottametre> {};
 
-struct hectare : alias_unit<square_hectometre, "ha"> {};
+struct hectare : alias_unit<square_hectometre, "ha", no_prefix> {};
 
 template<Unit U, Scalar Rep = double>
 using area = quantity<dim_area, U, Rep>;

src/include/units/physical/si/mass.h

@@ -50,7 +50,7 @@ struct exagram : prefixed_unit<exagram, exa, gram> {};
 struct zettagram : prefixed_unit<zettagram, zetta, gram> {};
 struct yottagram : prefixed_unit<yottagram, yotta, gram> {};
 
-struct tonne : alias_unit<megagram, "t"> {};
+struct tonne : alias_unit<megagram, "t", prefix> {};
 struct yoctotonne : prefixed_alias_unit<attogram, yocto, tonne> {};
 struct zeptotonne : prefixed_alias_unit<femtogram, zepto, tonne> {};
 struct attotonne : prefixed_alias_unit<picogram, atto, tonne> {};

src/include/units/physical/si/volume.h

@@ -52,7 +52,7 @@ struct cubic_exametre : deduced_unit<cubic_exametre, dim_volume, exametre> {};
 struct cubic_zettametre : deduced_unit<cubic_zettametre, dim_volume, zettametre> {};
 struct cubic_yottametre : deduced_unit<cubic_yottametre, dim_volume, yottametre> {};
 
-struct litre : alias_unit<cubic_decimetre, "l"> {};
+struct litre : alias_unit<cubic_decimetre, "l", prefix> {};
 struct yoctolitre : prefixed_alias_unit<cubic_nanometre, yocto, litre> {};
 struct zeptolitre : prefixed_unit<zeptolitre, zepto, litre> {};
 struct attolitre : prefixed_unit<attolitre, atto, litre> {};