Security and stability update @ Server @ MentDB Weak

This release includes important security fixes, stability improvements and bug fixes.
All users are strongly encouraged to update.

What's new

• Improved resilience of the internal database connections (automatic recovery, timeouts).
• Automatic database schema upgrade at startup for existing installations.
• Optional certificate and host key verification for FTPS, SSH and SFTP connections (new options in the connection JSON).
• New MQL function sql encode_std (standard SQL encoding for PostgreSQL, Oracle, SQL Server…).
• Many fixes in the MQL functions (math, dates, strings, files, CSV, REST, Excel).

Upgrade notes

• Copy the new src, core, lib, bin, docs, cas and jdk folders. The server now requires the bundled Java 21.
• Do not delete the data folder of an existing installation.
• New parameters are available in server.conf (see the comments in the file). Make sure start_scheduler is set, otherwise the jobs do not start.
• Web applications run with the dedicated web user: scripts called by an application outside app.* must be granted to web.
• Declare a short application name for the portal in each application configuration:
  json iobject "configuration" / portal_title "My app" STR;
• Behavior changes: math round now rounds half away from zero, application names are limited to a-z, 0-9, _ and -, and CSV lines with more values than columns now raise an error.