Fix vendored dep because upstream is non-responsive

Eventually this needs to be fixed in the textflow project by Phil,
but he has not done so in the half a year this bug has been known
to be there, so...

Closes #1470
Closes #1455

include/external/clara.hpp

@@ -111,6 +111,9 @@ public:
 			m_suffix = false;
 			auto width = m_column.m_width - indent();
 			m_end = m_pos;
+			if (line()[m_pos] == '\n') {
+				++m_end;
+			}
 			while (m_end < line().size() && line()[m_end] != '\n')
 				++m_end;