Incremental update for atmosphere rendering

Added mesh and initial shader for atmosphere.  Will add scattering at
shading effects later.  Mesh needs refinement.
Ignore earth_nmap.dds

Updated gitignore to not always request to commit the earth
normal/height-map file which is too large for github.
Transparent atmosphere mesh

Updated the sky mesh to integrate properly with the vertex and index
buffers (and their offsets).  Also added a render state configuration to
enable alpha-based blending when rendering the sky mesh.
Working on implementing ONeil's shaders

For realistic atmospheric scattering of light.
Updated atmosphere renderer

Atmospheric scattering effects shader works:
* from space the atmo looks pretty correct.
* for now, earth must be centered at origin :/

Added code to allow for culling of front faces instead of back (required
for sky shader)

Need to:
* fix location issue (recalc vector math)
* add other shaders:
** sky from atmo
** space from atmo
** ground from space
** ground from atmo
Speed improvements

Moved most of the scattering calculations back into vertex shader to
prevent it from wasting time.
Added sky from atmosphere technique

So that as you pass into the atmosphere it looks correct :)  You can see
the sun from within it! :)
Additional rendering

Working on rendering space w/ spaceFX;
Got ground rendering working from space;
Added ground from atmo

Ground now is correctly rendered when inside the atmosphere.
Displacementmap is default

Made the default render selection displacement mapping.
removed unneeded input layout

from old sky code.
Updated camera

Allows control to rotate the camera about the look vector using Q and E.
The mouse rotation is updated to accommodate for that.
removed old code

no longer needed (approximated collision detection.)
Large Update clouds, controls, movable planets

* Movement now works w/ arrow keys as well
* Cloud textures/normal maps have been added and can be rendered
** with bugs, needs to work w/ atmo better
* Planets no longer have to be centered at origin, camera pos must be
passed as relative to their centers.
* Removed extraneous variables and functions from effects.
* Added new depth stencil state for use with clouds when they work.
Tessellation fix

Fixed bug from code that should have not been removed that broke
tessellation.
Fixed cloud rendering bug

caused by code removal of course.
Updated design doc

Added HDR info to design doc; moved atmosphere to done.
Added more info about clouds, next atmosphere steps, and sun.
Tessellation Docs

For more advanced and higher-performance tessellation.
2 more docs

terrain rendering/tessellation.
Clouds working better

Clouds do not mess with atmosphere now; they are rendered without
writing to the depth buffer. ( so that they don't block the atmosphere
from writing to the pixel buffer because of the depth test.)  Working on
a way to get them to render when underneath them.