@UNQKVF[[u,]filename,"key","value"] : Add a key / file value pair to a UnQlite database.
|u||Optional flag that the key and value are Unicode (UTF16)|
|filename||Database opened with @UNQOPEN|
|key||Key to add or replace|
|filename||Store the contents of the file filename in the value|
|length||Length (in bytes) to write (or -1 for the entire file)|
The maximum file size is dependent on the amount of RAM and disk space available.
Returns 0 if successful, or the error text if not.
This example opens a database named "test.db", writes a key/file to the database, and then reads it back, saving it in a new file.
echo Testing file write and read