remove support for deprecated SVG format 1 table and embedded colorPalettes?

[anthrotype]

While working on implementing support for subsetting OT-SVG table (#534), I was reminded that our S_V_G_.py module supports two formats, whereas the OT spec defines only one format version 0.
There's an older, deprecated, format, unintuitively numbered format 1, whereas the current one is 0:

fonttools/Lib/fontTools/ttLib/tables/S_V_G_.py

Lines 19 to 37 in 71a986e

	Version 1 is the first SVG definition, implemented in Mozilla before Aug 2013, now deprecated.
	This module will decompile this correctly, but will compile a version 1 table
	only if you add the secret element "<version1/>" to the SVG element in the TTF file.
	Version 0 is the joint Adobe-Mozilla proposal, which supports color palettes.
	The XML format is:
	<SVG>
	<svgDoc endGlyphID="1" startGlyphID="1">
	<![CDATA[ <complete SVG doc> ]]
	</svgDoc>
	...
	<svgDoc endGlyphID="n" startGlyphID="m">
	<![CDATA[ <complete SVG doc> ]]
	</svgDoc>
	<colorPalettes>
	<colorParamUINameID>n</colorParamUINameID>
	...

I have never encountered a font with OT-SVG format 1. I wonder if we can drop support for it to simplify the code and reduce maintainance cost, as I set out to write unit tests for it.

Another thing I noticed is that, even for the current format 0, the fontTools S_V_G_.py module supports decompiling and compiling embedded color palettes, but the OpenType SVG spec has the corresponding field reserved to 0 and there is no mention of color palettes defined inside the SVG table itself, only references to external color palettes from the CPAL table.

I haven't followed these developments back in the days, but I imagine that this module was written at the same time as the OT-SVG spec was being drafted and it may contain legacy stuff that would later be dropped from the OT spec.

git log says the author is @readroberts so Adobe folks may know more/be interested in this

/cc @behdad @miguelsousa @cjchapman @justvanrossum

[anthrotype]

also /cc @jfkthame

[behdad]

Yep. Remove those all. They were never part of any standard.

[anthrotype]

Yep. Remove those all. They were never part of any standard.

ok, will do, thanks