Visitors forgetting programs [refs #44]

I forget to uncomment one mysql_query that is used for
mysql_affected_rows and interprets whether is program checked or not.
Variable id to block_id [refs #44]

For better coding - $id -> $block_id
Adding better error reporting [refs #44]

If error exists then report specific error.
Comments [refs #44]
Specific modify method for Meals [refs #44]

Overriding method modify for Meals model because in where clause is
visitor column not id.
Graph height change