New Setting for number of points when plotting functions

[MBerman9]

Line 322 of plotobjects.py hardcodes 100 points when plotting a function or fit. Sometimes, a higher resolution is preferable, so converting this into a setting would be appreciated.

qexpy/qexpy/plotting/plotobjects.py

Line 322 in d3578b2

return np.linspace(self.xrange[0], self.xrange[1], 100)