Make ssh pty usage optional
cleanup access methods
minor optimization
improve wchar output conversion
More wchar output conversion cleanup
moar wchar
ref-ify cell in put_cell()
Refactor put_cell() and parts of new_frame() into put_row().  Rework
and simplify display output optimization and line wrap handling.
Refactor get_row() and get_cell() calls in put_cell() inner loop, for performance.
Make last_frame a const ref, to eliminate a costly copy of the framebuffer on every screen refresh.
Temporarily disables scroll optimization.