Gallons/Quarts/Pints to Litres conversion is incorrect

The conversion is to/from US measures, yet this is not mentioned, and the conversion factors are wrong for Imperial measures as used here in the UK.

I suggest:
1. As a minimum, make it clear that US units are in use.
2. Ideally, provide a means to apply localisation other than by recompiling.

I have modified my version, to permanently use the Imperial conversion, thus:

In file gcalctool-6.6.2/src/unit-manager.c
Line 82 et seq:
        {NULL, "gallon", N_("Gallons"), NC_("unit-format", "%s gal"), "4.54609x", "x/4.54609", NC_("unit-symbols", "gallon,gallons,gal")},
        {NULL, "litre", N_("Litres"), NC_("unit-format", "%s L"), "x", "x", NC_("unit-symbols", "litre,litres,liter,liters,L")},
        {NULL, "quart", N_("Quarts"), NC_("unit-format", "%s qt"), "1.1365225x", "x/1.1365225", NC_("unit-symbols", "quart,quarts,qt")},

[Ubuntu 16.04 LTS]