Various fixes and improvements of gauges import: - Allow update of erased data (and thereby set erased to false) - Fix source_organization to work with ERDMS2 - Give ISRS of new and updated gauges in summary - Fixed reference of null pointers if revlevels are missing - Fixed reference of null pointer on update errors - Added ISRS to reference_code warning

# documentation
**/README*
**/docs
**/*.md

# backend binary
cmd/gemma/gemma

# Dependency directories
.buildbase
**/node_modules

# local dotenv environment variables file
client/.env.local

# Tags tables
**/TAGS