This patch add the missing select neighboring handles functions(gif):
These functions are essential for adding the missing Strip Slide and Split Roll trim functions, which now can be implemented easily after this Select Neighboring Handles patch is committed.
Not part of this patch(as single functions)
J, K, L + alt is select inside handles.
J, K, L + alt + Ctrl is select neighbor handles.
Unhide and unlock changed to use ctrl instead of alt(they should both be converted to toggles at some point)).