Update documentation
Merge pull request #143 from yous/documentation

Update documentation
prepare for postgresql
fix bugs in Board#leaves
Update gems
Merge pull request #144 from yous/update-gem

Update gems
implement highlighted in post

add highlighted column to posts
implement printing bold when post is highlighted
add shorcut to toggle highlighted
implement shortcut J,K in read_board_menu

implement #141
Merge commit '221baca02ae4a0d20896b59e6adcc8b17a6730e3'