client: improve pdf generation * Move general template interpretation code from Waterlevel.vue to lib/mixins.js. This is the first step to remove code redundancy as this code is similiar in four other places.

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

# backend binary
cmd/gemma/gemma

# Dependency directories
**/node_modules

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

# Tags tables
**/TAGS