We have a new, improved string type coming up in AK (OOM aware, no null
state), and while it's going to use UTF-8, the name UTF8String is a
mouthful - so let's free up the String name by renaming the existing
class.
Making the old one have an annoying name will hopefully also help with
quick adoption :^)
Because the result will be a float anyway get rid of the int parsing.
Also the grammar of SVG numbers matches the double parser grammar except
it can't have a sign but that should have been checked by the caller.
This is all still quite ad-hoc. Eventually these will both need to
support units (like with CSS Lengths) but for now we can continue only
using numbers.
I've chosen the name `AttributeParser` since it parses data from
attributes. Rather than duplicate the parsing of numbers and other
basic types, let's make use of this existing parsing code for parsing
the data for `<line>`, `<polyline>`, etc.
