BAP-5305: Add TIMESTAMPDIFF function
BAP-5305: Add TIMESTAMPDIFF function. Fix group name in test fixtures
BAP-5305: Add TIMESTAMPDIFF function. Rename function from TimestampDiff to Timestampdiff because of limitation in FunctionFactory
BAP-5305: Add TIMESTAMPDIFF function. Rename function from TimestampDiff to Timestampdiff because of limitation in FunctionFactory. Rename files
added timestampdiff function
Merge pull request #1 from orocrm/ticket/BAP-5305_timestampdiff

BAP-5305: Add TIMESTAMPDIFF function