Update gitignore & change mem.alloc to make

[blob1807]

Add ols.json (the lsp's config file) to the .gitignore.
Change mem.alloc to make as it's preferred:

• temp atlas: slices are preferred over & made to replace pointer offsetting/arithmetic + bounds checking is nice.
• font bitmap: might as well make a mulitpointer. it'll auto cast to a rawptr if need be.

When slicing up the images to add the atlas copy will copy the min length of dst & src.
I'll leave it up to you but make does return an optional error to be handled. It'll crash if unhandled, which it's a bad thing.

The allocation changes aren't really needed. It more's to do it how it's preferred to be done in Odin. Or more specifically how core does things.
Plus as a tutorial repo make + slices are easier (& safer) than raw dogging pointers.