Fix "unused variable" warning
mkxp.pro: Add 'EMBED' files to 'OTHER_FILES'

So they show up in the project tree in QtCreator.
Graphics: Setting 'fixedFramerate' to -1 disables frame limit

Can be useful for benchmarking
MRI-Binding: Adjust 'Kernel#caller' output to match RMXP
MRI-Binding: Don't refine Kernel#caller in RGSS3
Spacing/spelling
Quad: Don't discard VBO on each update

This never yielded any traceable performance gains.
I also apparently forgot to unbind the buffer after
updating.