Changes

Extend polyline tests

Rework poly point parsing
Change parsing of poly points to use a specific number parser insteads
of sscanf

Cleanup length parsing
remove the incorrect use of atof and use an API that does not require
the string to be copied to terminate with a null

Reimplement transform processing
remove use of sscanf and string duplication in transform processing

Reimplement color parsing

Improve number parse API

Reimplement parsing of viewbox
fixup tests that used non existant viewport attribute

Reimplement style processing

Improve attribute parsing with operation tables

Improve gradient parsing and generation

fixup paint parse

fixup named colour lookup

refactor path parse

improve svg parse initialisation/finalisation

Implement use element

Update test dir to add fuzzer configuration

Update AFL test corpus
in addition provides near complete coverage when used as unit test
vectors