Add the ->Page forward declaration for Repository
Change the page navigation coloring
Add a new testing function
Refactor select-page-titles by using map and filter instead of for
Add an indentation setting
Add a new view for new pages
Extract shell functions and move database logics from repository to page
Ditto
Remove the needless rw-lock argument
Trim the source argument of the new-page method
Add a new indent setting
Add a new method page-exists? and fix the bug select-page not to raise the exception