sqlBatch - make starting a transaction optional

[allie-wake-up]

I've found that using sqlBatch can cause large performance improvements for me, but sometimes I want to do more than 1 batch in a single transaction. I added an optional parameter so that the default behavior doesn't change and this is backwards compatible.

[EduFrazao]

@TheKiteEatingTree Hi. I'm sorry, but how can I use a sqlBatch with this plugin? I need to perform some large operations (with about 200k lines), and using a default INSERT within a transacion is very slow and even causing crashes. I did't find any way to execute it as batches. Can I use your approach? Can you share an example? Thanks!