Renamed csv-show-first-line-for-key-value to csv-show-jump-first-line-for-key-value
csv-show--next/prev-value: Now returns t when line was found, nil otherwise
Introduced csv-show--jump-first-line-for-key-value
Added doc string to csv-show-jump-first-line-for-key-value
Doc string fixes
Introduced csv-show--jump-to-first-value-change-of-column. Doesn't work yet.