GuiTreeView bug in buildVisibleTree

There was a bug in buildVisibleTree, it should be setting the RebuildVisible flag, not clearing it.

The clip rectangle did not appear to be updating when expanding items or calling scrollVisible, which expands all the items to make a particular item visible. This would cause part of the tree to be cut off.

Setting the RebuildVisible flag made the problem go away.
Alternate fix for GuiTreeView

Adding `mFlags.set(RebuildVisible)` to `GuiTreeView::onWake()` fixes the problem where the tree is not drawn correctly when nodes are expanded in the TorqueScript `GuiTreeView::onWake()` callback function.
Implemented physics collision for MeshRoad.

According to deepscratch's post in the forum:
http://www.garagegames.com/community/forums/viewthread/130181/1#comment-826897
Merge pull request #958 from skaughtx0r/Fix-GuiTreeView-buildVisibleTree

Fix gui tree view build visible tree
Fix #741

Local variable was used incorrectly. Did not result in any bugs, just a small amount of unnecessary network traffic.
Fix #258

No harm in it, and we can close the issue now.
firstPersonShadows:
follows up on https://github.com/GarageGames/Torque3D/commit/88bb577c82cd55be15b5db481558b3df7daa8066#diff-b8335f02a980665dd7dc953db7a637ca from way back when, and adds the script to turn on first person showing player shadows
Merge pull request #963 from Azaezel/firstPersonShadows_script

firstPersonShadows: