GL: Scatter plot point mimic MPL, curve picking using numpy
Merge remote-tracking branch 'upstream/master'
Graph: Add z parameter to addCurve
GL: Add z parameter to addCurve (pick need update)
Picker and curve z order.
Merge branch 'master' of https://github.com/t20100/pymca

Conflicts: PyMca5/PyMcaGraph/backends/MatplotlibBackend.py
Add "selectable" keyword.