Enhancements to deserialize: (1) Add the SQLITE_FCNTL_SIZE_LIMIT file control

to set a maximum size for an in-memory database, defaulting to 
SQLITE_MEMDB_DEFAULT_MAXSIZE or 1GiB.  (2) Honor the SQLITE_DESERIALIZE_READONLY
flag. (3) Enhance the TCL interface to support -maxsize N and -readonly BOOLEAN.
(4) Add the --maxsize option to the ".open" command and on the command-line for
the CLI.

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