Sub-second samples can overwrite each other for instruments that save files by timestamp

[amcmahon01]

Instruments, such as the ICI thermal cam, that index their output files in YYYY-MM-DD_hhmmss format will overwrite samples within the same second, keeping only the last one acquired. This has only occurred during sampling "slow downs", usually caused by RAM limits and swap file usage.

Solution:
Add global record number to all filenames to ensure they are unique.