Fix deleting part of a chunk
Fix deleting part of a chunk

Worksheet: When only part of chunk is deleted, pass the right lines to
chunk.delete_lines(). This was causing problems when deleting
at the end of the buffer.

johnrizzo1/reinteract,alexey4petrov/reinteract,jbaayen/reinteract,johnrizzo1/reinteract,rschroll/reinteract,rschroll/reinteract,alexey4petrov/reinteract,jbaayen/reinteract,jbaayen/reinteract,johnrizzo1/reinteract,alexey4petrov/reinteract,rschroll/reinteract