Adding the property wall type.

[EKAdebo]

Issues addressed by this PR

Closes #88

Adds in the property RoofType to the the SAPMarkup object

[EKAdebo]

@BHoMBot check compliance

[bhombot-ci[bot]]

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[FraserGreenroyd]

@BHoMBot check core @BHoMBot check serialisation

[bhombot-ci[bot]]

@FraserGreenroyd to confirm, the following actions are now queued: - check `core` - check `serialisation`