Fixed line search above

Previously, trying to find a line above wouldn't include the line above the
given location in the look up.

This means that trying to find the immediate line above would always fail.

Now the excluded lines are the given line and the lines below.
Merge branch 'fix-line-search-above'
[1.1.3] Updated CHANGELOG
Fixed Text exception

Previousy Text raised \InvalidArgumentExeption. It now raises
\Gnugat\Redaktilo\InvalidLineNumberException.
Merge branch 'fix-text'
Added tests for immediate line above searching
Added tests for search relative to first line
Merge branch 'edge-tests'
[1.1.4] Updated CHANGELOG