Inconsistent time in air density input

[ukmo-juan-castillo]

Describe the bug
If driving data is read from file, the consistency of the times in the file is checked in the W3WAVE subroutine. This is done to make sure that the driving data contains valid data for the time of the run. In the case of air density, the times read from the momentum driving data file are used, which is wrong and can cause false errors. To fix the problem, the variables TR0 and TRN have to be used instead of TU0 and TUN when testing the air density file.

To Reproduce
Any run using air density but not momentum driving data.

Expected behavior
The previously described configuration will fail will with the error:

' *** WAVEWATCH III ERROR IN W3WAVE :'
' NEW AIR DENSITY BEFORE OLD AIR DENSITY '
irrespective of the validity of the driving data.

Screenshots
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Additional context
The proposed fix has been successfully tested at the Met Office using the AMM15-SMC configuration.