[fpc-pascal] Lookup/Calculated fields implemented in TSqlite3Dataset

[Luiz Americo Pereira Camara]

I implemented Lookup/Calculated fields in TSqlite3Dataset at fpc trunk.

If someone is interested in this feature please test and give me the 
feedback because i don't use these features too much.

To make easier to setup the fields a recent Lazarus from svn is 
recommended (added support to the fields editor)

Luiz