Function parseLocation
Parses a --at value shaped like file
Example
parseLocation returns the file "a/b.d" and the line 15 for "a/b.d:15"
parseLocation("a/b.d:15") .should .equal(SourceLocation("a/b.d", 15));
Example
parseLocation throws for "a/b.d" without a line number
({ parseLocation("a/b.d"); }) .should .throwException!Exception .withMessage("The `--at` value `a/b.d` must look like file.d:42");