[Bf-taskforce25] Unique sequence strip names

[Campbell Barton]

Some of the sequencer operators would benefit from sequencer strips
having unique names, (Sequence * types)

adding an effect for instance, would be nice if you could give the
operator args like this...
bpyop.sequencer.add_strip_effect(type='CROSS', seq1="anim1", seq2="black")
...rather then setting up the selection and running it.

For most functions unique names per metastrip would be enough but
since you can make and separate metastrips while editing, making the
names per scene seems less likely to cause collisions while editing.

Even though the Sequence struct is already pretending to be library
data, I cant see any reason to make strips true  library data (other
then for consistency).
It would seem enough that each strip has a unique name per scene.
since Sequence strips have no inter-scene relationships.

The main advantage with strips being library data is for use in multiple scenes.
But this (like multi user objects), would mean the position in the
animation would also be shared between scenes, so it seems a lot less
useful then a camera in multiple scenes for eg. A strip in multiple
scenes would be problematic if scenes frame rates dont match.

having real Sequence Strip library data would allow appending strips
from another blendfile and access strips globally by name, but I'm
still not convinced its worthwhile.

Sequence strip names can work like bone names, do_versions for older
files can make the names unique, nothing currently relies on matching
the names so this wont break anything.

Id like to go ahead with this soon, let me know if there is any
problems with this proposal.

-- 
- Campbell