Grepview - Introduce a new intermediate level corresponding to lines
Summary: Add items that correspond to whole lines which is useful if a line contains multiple matches.
Test Plan:
Tests pass
Reviewers: KDevelop, apol
Reviewed By: KDevelop, apol
Subscribers: kdevelop-devel
Tags: KDevelop
Differential Revision: https://phabricator.kde.org/D21580