smearing options incorrect on show2D and show1D in fitpage

[butler]

only the "no smearing" radio button should be enabled when no model is chosen. This is true when opening a new FitPage but if one immediately clicks on show2D the custom pinhole option is enabled (the only valid option in 2D when no smearing data is available). If the show1D option is now pressed, instead of going back to the original options, both custom pinhole and custom slit are now showing as available (again the only options available if the data has no smearing info).

This is because the _set_smear_buttons() method does not check for the existence of self.model

This should be a trivial fix and given the smear fixing work already in 4.2.1 suggest it get added to that release

[butler]

In aa9928ee015e877e08647a0d23fd95c877f6cf9c/sasview:

Fix behavior of smear buttons

Added check for self.model to _set_smear_buttons and more info logging.
Smear buttons should now be enabled depending on 2D vs 1D, model or not,
and resolution data available or not.

Addresses #1222

[GitHub <noreply@…>]

In a13c41b8f2613602a02054c4a6216ecb4b012a8d/sasview:

Merge pull request #203 from SasView?/ticket_1206

Ticket 1206 - fix problems in smearing sizer

Fixes #1206
Fixes #1222