refactored shader building

package.json

src/mol-gl/shader-code.ts

src/mol-gl/shader/chunks/color-vert-params.glsl

src/mol-gl/shader/chunks/common-frag-params.glsl

src/mol-gl/shader/chunks/common-vert-params.glsl

src/mol-gl/shader/chunks/common.glsl

src/mol-gl/shader/chunks/matrix-scale.glsl

src/mol-gl/shader/chunks/read-from-texture.glsl

src/mol-gl/shader/chunks/size-vert-params.glsl

src/mol-gl/shader/chunks/texture3d-from-2d-linear.glsl

src/mol-gl/shader/chunks/texture3d-from-2d-nearest.glsl

src/mol-gl/shader/direct-volume.frag

src/mol-gl/shader/gaussian-density.frag

src/mol-gl/shader/histogram-pyramid/sum.frag

src/mol-gl/shader/lines.frag

src/mol-gl/shader/lines.vert

src/mol-gl/shader/marching-cubes/isosurface.frag

src/mol-gl/shader/mesh.frag

src/mol-gl/shader/mesh.vert

src/mol-gl/shader/points.frag