Red bean php3 3 x

Hi,

I've faced some problems attempting to integrate RedBean with my modest framework. I'm using 'Model_' as naming convention within the framework to autoload Models, however RedBean uses the same prefixes and attempts to load the models itself.

I'm not willing to replace the whole model mechanism with RedBean, so instead I've added the RBModel_ prefix to RedBean's naming convention and added a flag that completely disables the use of the 'Model_' prefix.

I'd have written a unit test for it, but I can't make out how your unit test framework works. It is a smallish change anyway.