[Ohrrpgce] SVN: teeemcee/8661 sliceedit: allow editing an external slice collection

[subversion at HamsterRepublic.com]

teeemcee
2017-04-20 08:29:37 -0700 (Thu, 20 Apr 2017)
366
sliceedit: allow editing an external slice collection

This is a third alternative to editing an existing slice tree and the
'indexed' slice editor.

Change the way F3 import behaves: now you are asked whether to overwrite
the existing slice tree, or want to edit an external file. Maybe these should
be split up to two different keys, since they're quite different.
---
U   wip/sliceedit.bas
U   wip/sliceedit.bi