inc version before add new features
divide funtions into Skygrepe::Database and Skygrepe::Formatter
add Skygrepe::Context to keep context for pagination, but nothing implemented for it.
rename Database to Condition, move Database object and argument 'keyword' to Context
add implementation for pagination
quit when result is shorter than limit
accept command character instead of string to make operation easy
unescape message by using CGI.unescape_html
accept ENTER to make space lines
show keyword with highlight