Validation for temperature and pressure

[mattdowdell]

Temperature and pressure are currently validated to ensure they're numbers. Pressure is also checked to be greater than 0. This should be improved to set reasonable limits on their permitted range.

For temperature this could be the working range of the sensors +5(?)%. Pressure varies relatively little for what I would expect to be normal usage so it's just a matter of defining something sensible.

Once these limits have been implemented tests should be added to:

• Test a number above the upper limit fails.
• Test a number below the lower limit fails.
• Test a number just above or at the lower limit passes.
• Test a number just below or at the upper limit passes.