[CHORE] Better variable names in Amount#parse_quality.
[CHORE] Better variable names in Amount#parse_quality.

darkdarkdragon/ripple-lib,wilsonianb/ripple-lib,ripple/ripple-lib,darkdarkdragon/ripple-lib,darkdarkdragon/ripple-lib,ripple/ripple-lib,wilsonianb/ripple-lib,ripple/ripple-lib,wilsonianb/ripple-lib,ripple/ripple-lib