add optional `invisible' property to `weechat-print-line'

Signed-off-by: Moritz Ulrich <moritz@tarn-vedra.de>
add invisible property instead of not printing

Signed-off-by: Moritz Ulrich <moritz@tarn-vedra.de>
Add `weechat-toggle-hidden'

Signed-off-by: Moritz Ulrich <moritz@tarn-vedra.de>
add keybinding for `weechat-toggle-hidden'

Signed-off-by: Moritz Ulrich <moritz@tarn-vedra.de>
Recenter window when it's necessary

Signed-off-by: Moritz Ulrich <moritz@tarn-vedra.de>
recenter window automatically

Signed-off-by: Moritz Ulrich <moritz@tarn-vedra.de>
auto recenter on toggle hidden

Signed-off-by: Moritz Ulrich <moritz@tarn-vedra.de>
Merge branch 'hidden-lines'

Signed-off-by: Moritz Ulrich <moritz@tarn-vedra.de>