Fixed the category not loading bug

the problem is like this,
once 'once' is set to 0 and 'oldtotal' is 10, i.e you fetch more
articles when the list has 10 titles but then quickly shift category,
in the new category, you wont ever get 'once' to become 1.
This has been explained in the comments, now the loading of all the
categories have been fixed and the logic used to ensure proper
fetching of articles have been explained in detail.

I deleted some needless comments and edited some.

Signed-off-by: Aditya Prasad <adityaprasadiskool@gmail.com>