First commit of extension-tao-outcomerds :
- Install and uninstall scripts
- ontology
- implementation of writable and readable ResultStorage
it doesn't yet write properly (and maybe read)
modify database schema and change storage of variable
modify data retrieval with new schema and imporve perf
add identifier to variables table
change storage rules
Return variable in an object
remove extension's statement entry on uninstall
add item in storage
use variable getter to have value for a key