PyplotViewer upgrade

To make the `PyplotViewer` more handy there are things to add and also some API improvements to be done
- [x] Make the coroutine `__call__` more straightforward (it should return the coroutine, but always the same one)
- [x] Change set_clim to something which is actually understandable
- [x] Colormap change
- [x] Make it pausable
- [x] add 1D plots (https://github.com/ufo-kit/concert/commit/952fc766caf9bd63a240ef9d4160ba96b465274a)
- [x] Add axes title
- [x] Add x and y axes title for `PyplotCurveViewer`
- [x] Update CHANGES