Add 'Clone Tab' action for cloning current tab

This action will create new tab/session using the same settings(command,
colors, etc) used in current tab/session.

At this moment, this action does not always clone current tab/session
100%. For example, If you change the scrollback setting of current
session temporarily through context menu or dbus method, this action
won't clone the temporary change. Another example is the tab title.

On the other hand, this action works quite well with command line
options(-e, -p, etc) and the 'konsoleprofile' utility.

FEATURE:254976
FEATURE:292518
FIXED-IN:4.9.0

REVIEW:103859

DIGEST: