Enhance SVG 1.1 implementation

[cocobean]

During unit testing with SVG 1.1 Second Edition Test Suite, librsvg-2.40.21 passed all tests within the provided SVG 1.1 test suite except one test (see ref) on Haiku hrev54138.

Review possibility of including librsvg-2.40.21 with Haiku distribution as a baseline SVG 1.1 library implementation for further internal developments and testing (i.e. Webkit, I-O-M, etc).

Ref: ​https://github.com/haikuports/haikuports/pull/4944

[waddlesplash]

WebKit has its own SVG parser, and we do not maintain it. So does I-O-M, because it is for importing SVGs, not rendering them. So this is not possible or necessary.

[pulkomandy]

For WebKit, the parser is working fine, the problem is (as usual) in translating the drawing commands to BView APIs. For example, dotted and dashed lines are not available in BView, and there are many similar problems.

Note that WebKit also has much more than just showing SVG: it needs to animate them, there is DOM access allowing manipulation from Javascript, and so on. I expect librsvg would allow similar things, but it is probably too complicated for inclusion as a baseline component (it depends on Rust, in current versions).

For Icon-O-Matic I will look into some of the problems, I'm considering either using nanosvg, or, if that doesn't work, fixing the existing parser which is based on an example from the agg library.