Consider zoom when culling billboards.

screenScale represents the current zoom factor, but may need some
revision because I'm not sure if what it's doing is technically correct.
It is used to multiply the culling distance for cells, as well as the
fading distance.
Added comment.
Elastic ease fix

Elastic ease used an arcsinus function where it should have used a sinus
function.
Update README.md
Merge branch 'development' of https://github.com/thecelloman/Torque3D
Merge remote-tracking branch 'upstream/master'
Updated README.md

Added information on where to find the pre-compiled versions.
Fix engine API copy/paste errors (typo).
Bug fixes for alternative zip layout and define to toggle it on
Update squish library to 1.11
Removed hard coded directory paths

- Removed references to core directory.
- Switch some references to tools directory
- Added preferences variables where appropriate
Merge pull request #248 from DavidWyand-GG/HardCodedPaths2

Removed hard coded directory paths
Updating libpng to v1.5.14 and zlib to v1.2.7

Since libpng has a dependency upon zlib, both updates were combined for one commit/pull-request.
Merge pull request #250 from thecelloman/updatelibpngandzlib

Updating libpng to v1.5.14 and zlib to v1.2.7
Merge pull request #243 from thecelloman/updatesquish

Update squish
Update TinyXML to v2.6.2
Merge pull request #255 from thecelloman/updatetinyxml

Update TinyXML to v2.6.2
Tools GuiProfile Separation.

This effectively duplicates (where necessary) and moves tools specific GuiProfiles out of the core and into the tools.  This will allow future modifications to either the game guis or tools guis that use these profiles to not conflict with each other.
Remove unused and (partially) unworking UnifiedShell.
Merge pull request #259 from thecelloman/toolsguiseparation

Tools GuiProfile Separation.