- Also exposed the sys crate's ImPlotRange, ImPlotLimits and ImPlotPoint
to the user as well as changing the limit-setting interface to using
those. I'm not super sure about doing this yet though, because it is
more verbose for no real reason to the user and for the purposes of
the abstraction it may be better to add facade types anyway.
- There is no protection against calling things like `is_hovered` from
outside a plot. Will need to think about how to make this impossible
by design - we could for example pass an object to Plot's closure
that has these methods, and that object is not created anywhere
else.
- Copied the trick from imgui-rs to notice if a begin() is left
unmatched
- Changed plot_line to be a struct, but might go away from that
again. Initial idea was to add things like setting markers and
colors to this as struct methods, but it seems this will lead
to lots of code overhead compared to the pushing and popping
stylevars approach taken in the C++ implementation.
