Add some shader related functions and add shader support for Modern OpenGL and flip the Y to match what GML shaders expect the Y coordinate to be and change texture settings.

[Classic0306]

adds: shader_set, shader_reset, shader_current, shader_get_uniform, shader_get_sampler_index, shader_set_uniform_f, sprite_get_uvs, texture_get_texel_width, texture_get_texel_height, texture_set_stage and font_get_uvs

the Y coordinate for rendering (for both modern and legacy OpenGL, I didn't test legacy at all ngl) has been flipped to match what shaders expect, only MATRIX_WORLD_VIEW_PROJECTION has been made for the gm_Matrices built-in uniform for shaders.

It makes me feel bad to keep others waiting so I want to submit this even if it is a bit incomplete still

I only tested DELTARUNE Chapter 3 and 4, tested Tenna's fight, tested Susiezilla and the ripple effect in Chapter 4 and a very tiny bit of the Second Sanctuary