[Chart] Chart V1.2

[Tim Docker]

Hi,

I've just uploaded version 1.2 of Chart to hackage. This has a small 
number of changes, but gets a major version bump because the simple API 
has moved into it's own package (Chart-simple). This addresses a few 
dependencies issues. There are a hand full of other fixes, and a 
constraint update to permit the most recent diagrams release.

I've never been especially happy with the contributed Simple API. At 
some stage I'd like to deprecate it and replace it with
something cleaner. For now, at least, it has been lifted out of the 
chart core.

Cheers,

Tim