Changes
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Preserves Wimp poll mask through the filters.
-> prevents crash from task not expecting to get a pointer motion event

Add Always Confirm Delete option
-> If set, overrides Filer preference and insists on confirmation for delete operations.

Techwriter save doesn't make duplicates
-> Techwrite saves by doing a create new/delete old/rename
-> adjust interpretation of the action queue to allow for this

Impression docs don't appear with their icons at boot up
-> Adjust sprite import so that we don't just check for !Sprites22 (eg) at startup
   as Impression docs don't have one.

Fix carousel
-> Doesn't complain for invalid files in a directory; just skips them

Close icon now works on Set Type window
SetType option greyed out if only inaccessible files are selected.
