* Revised PerspectiveCamera.

- Allows extra skew for stereo rendering.
- Allows to query effective FOV angle (considering .zoom).
- Proper copy / serialization of all properties.
- Tidier, single code path frustum calculation.
- No longer uses ProjectionMatrix.makePerspective.

* Revised PerspectiveCamera physical interface.

- 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

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`

Fixes #5570

It shouldn't be needed as Camera .clone() is already copying .projectionMatrix.

Matrix4's static methods makeFrustum, makePerspective, makeOrtho are now normal non-static public methods. Fixes #1615.

* Camera is now a base object. PerspectiveCamera should be used instead. Figured out a way to show a warning when misused.
* OrthoCamera is now OrthographicCamera.
* Removed `target` from Camera.

Misc
* Renamed Trident to Axes.

* Camera.useTarget is now false by default. Updated some of the examples. I tried to remove target altogether (and use lookAt every frame), but I found that WebGLRenderer's ShadowMaps uses a camera with target. Will try again at some point.
* Object3D.lookAt now checks if it's a Camera and does the inverted view.
* Quaternion glitch reported at #595
* Added .name to Material
* WebGLRenderer .clear() to .clear( color, depth, stencil ). All of them true by default.

This buggy pattern ("something = parameter || nonzero value") exists at more places though elsewhere setting to zero doesn't make that much sense (e.g. in geometries).

Not sure if we should change it everywhere to proper pattern ("something = ( parameter !== undefined ) ? parameter : value").

Maybe it would be good for establishing habit. I remember fixing this buggy pattern long ago but it just keeps popping up.

Examples in another commit

Added FlyCamera (thanks to James Baicoianu). Added specular map to normal map shader. Added WebGL Earth FlyCamera demo.

Changed normal map shader to multiply specular component with diffuse weighting as specular highlights were appearing in the dark parts.

Changed camera look speed in minecraft and terrain demos, they were too fast - I guess as everything got faster with antialiasing off.

Reenabled antialiasing in few demos where it was too ugly without (basically anything with lines and without postprocessing).

Fixed again spurious invisible characters in empaempa's code (which are breaking everything and are hard to hunt as they look like spaces).