Handle NoneType in plot_windmatrix to Prevent Errors

[msandmer]

Issues addressed by this PR

Closes #276

plot_windmatrix failed if self.source == None.
Added a if-loop to handle the NoneType in plot_windmatrix to prevent errors when creating the plot title.

Test files

run python automated testing batch file

Changelog

Additional comments

[Tom-Kingstone]

Changes look good now, and running windmatrix without a source no longer produces errors.

[Tom-Kingstone]

@BHoMBot check required

[bhombot-ci]

@Tom-Kingstone to confirm, the following actions are now queued:

• check code-compliance
• check documentation-compliance
• check project-compliance
• check core
• check null-handling
• check serialisation
• check versioning
• check installer

[Tom-Kingstone]

@BHoMBot check unit-tests

[bhombot-ci]

@Tom-Kingstone to confirm, the following actions are now queued:

• check unit-tests

There are 9 requests in the queue ahead of you.

[Tom-Kingstone]

@BHoMBot check dataset-compliance
@BHoMBot check copyright-compliance

[bhombot-ci]

@Tom-Kingstone to confirm, the following actions are now queued:

• check dataset-compliance
• check copyright-compliance

[Tom-Kingstone]

@BHoMBot check ready-to-merge

[bhombot-ci]

@Tom-Kingstone to confirm, the following actions are now queued:

• check ready-to-merge

There are 1 requests in the queue ahead of you.