fix `weechat-merge-alists' and merge changed lvars

Signed-off-by: Moritz Ulrich <ulrich.moritz@googlemail.com>
Don't set `weechat--buffer-hashes' to nil when disconnecting

Signed-off-by: Moritz Ulrich <ulrich.moritz@googlemail.com>
Delete trailing whitespaces

Signed-off-by: Moritz Ulrich <ulrich.moritz@googlemail.com>