Add file path and other internal improvements

[ercius]

SMV header improvements:

• the file loaded is added to the SMV header
• the current time is added to the SMV header instead of some random date in 2021
• detector_SN (serial number) is now set to 1 insead of unknown
• the line endings for SMV are enforced to be "\n" (linux line endings) since most processing programs assume this. Data exported from Windows should now be readable in adxv and xds

Other improvements

• The actual memory required (3x the "ragged array") is reported in the terminal
• the name of the opened file is retained and displayed in the status bar

[ercius]

This fixes #17 and #20