score
Parses a string representation of a score into a Score. The input must be a string ending in either ".0" (for whole points) or ".5" (for half points).
Return
A Score initialized with the correct internal value.
Parameters
score
The string to parse (e.g., "1.0", "2.5").
Throws
if the score format is invalid or does not end in .0 or .5.