Rename batching project settings in preparation for GLES3

[lawnjelly]

Project Settings

As it now seems like we will soon have GLES3 batching working using the same intermediate layer as GLES2, it makes more sense to reuse the same batching settings for both renderers rather than duplicate project settings for GLES2 and GLES3.

Light scissoring area threshold

I've also made a very slight tweak, that I'm interested in opinions on. The light scissor area threshold is currently a value between 0.0 and 1.0, being the fraction of the screen area that needs to be 'saved' by a scissor operation in order to activate scissoring.

Although this is simpler to understand(!) it does meant that many of the useful values are very close to 0.0 : i.e. 0.01 and thereabouts, which represents 1 hundredth of the screen area. In order to make this more 'editable' I've experimented here with changing this to a power of 4 relationship.

i.e. value 0.3 ^ 4 = 0.0081

Anyway I'm open to suggestions / changes on that front. It's hard to explain anyway aside from it being a vague figure between no scissoring and full scissoring.

Notes

• I've discussed the batching for GLES3 in 4.x, reduz suggests instancing may help for 4.x. However any changes towards instancing will be some time in the future, so I'm fine with using the current system for 3.x, so this category change still makes sense (there will still be a lot of commonality even if we use some instancing).
• As always I'm open to ideas on better names / categories etc. 👍

Preview

[akien-mga]

Thanks!