DirectX9 Renderer bug fix

ZBuffer set to false to stop patches of the gui to complete disappear in
some states.
Gets Current Texture incase the texture was changed before the render of
the GUI.
Set Texture to NULL for fail safety.
Fix GroupBox and ColorPicker, add multi-line label to groupbox unit test
SFML static premake fix
Update jeremieroy's implementation of multilinetextbox to conform to the standards and work with the current master branch.
source: https://github.com/garrynewman/GWEN/pull/38
Merge pull request #54 from topblast/master

DirectX9 Renderer bug fix
Merge pull request #58 from pixellegacy/feat-multitextbox

jeremieroy's implementation of multiline textbox, updated for current
Merge pull request #57 from pixellegacy/fix-renderissues

Fix GroupBox and ColorPicker, add multi-line label to groupbox unit test
Merge pull request #56 from pixellegacy/fix-sfmlstatic

SFML, windows, and static