Improve db

[lagleki]

#131 issue is to be taken into consideration, e.g. adding a new table for tags for particular meaning like we now have one for notes. Changing from "word => language => definition" to "word => meaning => language => definition"

The current database and JVS 1.0 should stay compatible with the new one. E.g. every new definition in JVS 1.0 will just have a new meaning in JVS 2.0. This is also how we can upgrade the db while being able to still retain JVS 1.0 functionality.