Server should be able to manage thousands of databases

[lvca]

Once you open a database on an ArcadeDB Server, the server keeps the database open until it's expressly closed (/close HTTP command). For use cases with hundreds or even thousands of small databases hosted on one server, it would be useful to have an LRU on the databases, so that the least used database is closed. This could be a server setting:

arcadedb.server.maxOpenDatabases = 100 (default = 100)

We could also introduce a maximum timeout for an unused database to remain open on the server. After the timeout is expired, the database is automatically closed.

arcadedb.server.closeDatabaseTimeout = 0 (default = 0)