Fixed issue #1928: Hotkeys in "Show log" dialog for navigating back / forward

Initial design by Sven Strickroth.

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Signed-off-by: Yue Lin Ho <b8732003@student.nsysu.edu.tw>
Navigate selection history via log jump up/down button

Signed-off-by: Yue Lin Ho <b8732003@student.nsysu.edu.tw>