Add additional length units.

Resolves #1.

src/si/length.rs

@@ -35,5 +35,28 @@ quantity! {
         @attometer: prefix!(atto); "am", "attometer", "attometers";
         @zeptometer: prefix!(zepto); "zm", "zeptometer", "zeptometers";
         @yoctometer: prefix!(yocto); "ym", "yoctometer", "yoctometers";
+
+        @angstrom: 1.0_E-10; "Å", "ångström", "ångströms";
+        @astronomical_unit: 1.495_979_E11; "ua", "astronomical unit", "astronomical units";
+        @chain: 2.011_684_E1; "ch", "chain", "chains";
+        @fathom: 1.828_804_E0; "fathom", "fathom", "fathoms";
+        @fermi: 1.0_E-15; "fm", "fermi", "fermis";
+        @foot: 3.048_E-1; "ft", "foot", "feet";
+        @foot_survey: 3.048_006_E-1; "ft", "foot (U.S. survey)", "feet (U.S. survey)";
+        @inch: 2.54_E-2; "in", "inch", "inches";
+        @light_year: 9.460_73_E15; "l. y.", "light year", "light years";
+        @microinch: 2.54_E-8; "μin", "microinch", "microinches";
+        @micron: 1.0_E-6; "μ", "micron", "microns";
+        @mil: 2.54_E-5; "0.001 in", "mil", "mils";
+        @mile: 1.609_344_E3; "mi", "mile", "miles";
+        @mile_survey: 1.609_347_E3; "mi", "mile (U.S. survey)", "miles (U.S. survey)";
+        @nautical_mile: 1.852_E3; "M", "nautical mile", "nautical miles";
+        @parsec: 3.085_678_E16; "pc", "parsec", "parsecs";
+        @pica_computer: 4.233_333_333_333_333_E-3; "1/6 in", "pica (computer)", "picas (computer)";
+        @pica_printers: 4.217_518_E-3; "1/6 in", "pica (printer's)", "picas (printer's)";
+        @point_computer: 3.527_778_E-4; "1/72 in", "point (computer)", "points (computer)";
+        @point_printers: 3.514_598_E-4; "1/72 in", "point (printer's)", "points (printer's)";
+        @rod: 5.029_21_E0; "rd", "rod", "rods";
+        @yard: 9.144E-1; "yd", "yard", "yards";
     }
 }