Bug 474449

When Okular uses tabs for opening new files, if the user open multiple files while searching for a specific data, the number of tabs becomes significant, 

1) so if the user finds the target information, then maybe it becomes necessary to close other tabs excluding the found file, 

2) and if the user doesn't yet found that information he/she needs to open more files to continue searching, in this case it's necessary to close all opened files to free tabs' space without closing the whole app,

The same scenario can be encountered with any internet browser like Firefox, which partially solved the issue by providing a contextual menu that opens after right-clicking on any tab, and it provides the following functions:
- Close current tab
- Close multiple tabs : other tabs, tabs to left and tabs to right

It would be great if Okular offers the same contextual menu with some close functions, especially:
- close other tabs, tabs to left and tabs to right, 
- plus a possibility to close all tabs.