Add a way to control style handling in the export module.

It is now possible to select whether the style module are to be
appended to the current picture history or as before just replacing
the corresponding module in the history.
Spots IOP: legacy_params(): adapt for latest mask changes

Shame on me, this should have landed before 1.6,
it was lying in load-raw-raw-data branch (PR #619) since at least Aug 5,
but i totally forgot about this particular commit...

Consequences:
for an image with spot v1, opened from mid summer until now:
	upgrade to v2 = results in broken mask
Now:
	upgrade to v2 = ok...
Merge branch 'export-style-dup-module'

* export-style-dup-module:
  Add a way to control style handling in the export module.
ImageIO Format TIFF: use scanline-based I/O. Fixes #10230

Also do check for TIFFWriteScanline return code and abort on first error.

As for TIFFTAG_ROWSPERSTRIP: (from specs)
Choose RowsPerStrip such that each strip is about 8K bytes, even if the data is not compressed, since it makes buffering simpler for readers. The 8K value is fairly arbitrary, but seems to work well.
That means,
	StripSize = 8 Kbyte
	RowSize = WIDTH pixels * 3 * X bit/pixel
	RowsPerStrip = roundf(StripSize / RowSize)
And in 99%, RowsPerStrip is 1.