API function `move_to_meta` should move strips without changing context
data like `MetaStack` that tells UI which meta strip should be
displayed and operated upon.
`SEQ_time_update_sequence` relied on `MetaStack` to update meta strip
content length. Instead of changing function `SEQ_time_update_sequence`,
use function `SEQ_time_update_meta_strip_range` directly. This is
because caller would have to be aware of parent meta strip that needs
update anyway.
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