Coding style (aside_feed.phtml)

See https://github.com/marienfressinaud/FreshRSS/issues/646
BREAK CATEGORIZE SYSTEM!

And begin big changes.

See https://github.com/marienfressinaud/FreshRSS/issues/646
Move creation of categories in a new Controller

Category names are 255 chars max
Move empty cat action in the new Controller

feedController::delete is simpler than before.
Improve coding style

See https://github.com/marienfressinaud/FreshRSS/issues/646
Additional information about cat configuration

See https://github.com/marienfressinaud/FreshRSS/issues/646
Move deletion of categories into new Controller

Fix i18n (occured -> occurred)

See https://github.com/marienfressinaud/FreshRSS/issues/646
Cat updating system works

Add a submit button
Each box contains a specific form

See https://github.com/marienfressinaud/FreshRSS/issues/646
Improve design of .box

See https://github.com/marienfressinaud/FreshRSS/issues/646
Load feed configuration on the same page

Need improvements

See https://github.com/marienfressinaud/FreshRSS/issues/646
Simplify configureController

Remove useless code for category configuration.

See https://github.com/marienfressinaud/FreshRSS/issues/646
Reorganize subscription management code

There is still a lot of work to do. Some links are broken.

See https://github.com/marienfressinaud/FreshRSS/issues/646
Add selected feed on main subscription page

- When an id is given, corresponding feed is displayed
- Refactor code
- Improve coding style

See https://github.com/marienfressinaud/FreshRSS/issues/646
Fix links for feed management

See https://github.com/marienfressinaud/FreshRSS/issues/646
Fix problem when deleting default category

This is not allowed!

See https://github.com/marienfressinaud/FreshRSS/issues/646
Design of the slider

See https://github.com/marienfressinaud/FreshRSS/issues/646
Fix close slider when a feed is selected

See https://github.com/marienfressinaud/FreshRSS/issues/646
Better import icon

See https://github.com/marienfressinaud/FreshRSS/issues/646
Merge branch '646-new-cat-system' into dev