FileClientModel initializes FileClientGroup without proper points_class

[jmmgenerac]

Because the FileClientModel initializes its FileClientGroup parent class without referencing the FileClientPoint class, all points in the FileClientModel have the generic device.Point class instead of the file.client.FileClientPoint class.

One benefit of using the FileClientPoint class is that it contains a read() method, unlike the device.Point class which does not.

pysunspec2/sunspec2/file/client.py

Lines 54 to 55 in 642f1af

	FileClientGroup.__init__(self, gdef=gdef, model=self, model_offset=0, group_len=self.model_len, data=data,
	data_offset=0, group_class=group_class)

Should be:

 FileClientGroup.__init__(self, gdef=gdef, model=self, model_offset=0, group_len=self.model_len, data=data, 
                          data_offset=0, group_class=group_class, point_class=point_class)

[jmmgenerac]

See pull request #69