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
Merge branch 'development' of https://github.com/GarageGames/Torque3D into development