Reverts: Fix double click can only select text within visible region

Partial revert of 914067d14a6a27b59bba1c53cc18cb67eb9811fc

Change to use old code while leaving (not used) new code in.

Fixes reproduciable crashes:
Konsole::TerminalDisplay::findWordEnd()
Konsole::TerminalDisplay::charClass(image[j]); -> invalid location

I was not able to get the triple click code to crash which was the
previous patch to this.

BUG: 338997
FIXED-IN: 18.04