Geometry: Renamed .sortFacesByMaterial() to .sortFacesByMaterialIndex(). See 9ca9003e.

Removed IndexBufferAttribute. Promoted index attribute to BufferGeometry. Maybe .addIndices() instead?
/ping @benaadams

- Better inheriting of `clone` + `copy` methods where appropriate. This is done by calling `new this.constructor()` in parent classes. `this.constructor` refers to the current instance's constructor, so it should all compose nicely;

- Pass in attributes directly as arguments to constructor when cloning, where appropriate (if arguments pattern is different from parent class). This mean `copy` isn't relied on to set those attributes.

- Change order of `clone` in some files (for better visibility into its relationship with `copy`, and to maintain consistency; can return to previous order if necessary);

- Fix CubeTexture's clone method

Clear the target data before pushing new vertices and faces

eg. / e.g.
vertice / vertex
fullframe / full-frame
todo / TODO
unreckognized / unrecognized
ontop / in front
initialise / initialize
unforms / uniforms
overriden / overridden
interpolatation / interpolation
subsurve / sub-curve
Catmull-rom / Catmull-Rom
consruct / construct
colinear / collinear
perpenicular / perpendicular
minimim / minimum
segements / segments
speficied / specified
compatable / compatible
egde / edge
initalization / initialization
shiftet / shifted
childrens' / children's
ambigious / ambiguous
barycoordinates / barycentric coordinates
equi distance / equidistant
equidistance / equidistant
ist / is

And remove one `console.log`