Update current page func and add missing location

I have add this function to get the code much more readable. 

```PHP
function osc_is_current_page($location, $section) {
        if( osc_get_osclass_location() === $location && osc_get_osclass_section() === $section ) {
            return true;
        }
        return false;
    }   
```

I added missing location
 * osc_is_edit_page()
 * osc_is_item_contact_page()
 * osc_is_list_alerts()
 * osc_is_contact_page()
 * osc_is_recover_page()
 * osc_is_forgot_page()
 * osc_is_recover_page()
 * osc_is_change_email_page()
 * osc_is_change_username_page(
 * osc_is_change_password_page()
 
I moved osc_is_homepage() in first.

I also moved some functions to regroup them by type (item, user).
Merge pull request #1506 from groomain/patch-8

Update current page func and add missing location