Add a default guard on data too long for column sql error

[mhlsf]

I made a sql column using the ->string(255) of TdbmFluidSchema.

If I try to insert a value bigger than the max size of the string, I get the expected PDOException : SQLSTATE[22001]: String data, right truncated: 1406 Data too long for column 'name' at row 1 unless I set a rule in the Model.

Maybe Tdbm should generate a condition to avoid this kind of error by either integrating a validator or proposing an option to automaticaly generate a condition in the model that throw an error message as this can be redundant.