Update TextBox.h

Added PasswordTextBox class
Update TextBox.cpp
Merge pull request #53 from topblast/master

PasswordTextBox
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
Ignore generated files
Fixed compiling issues with some compilers
SFML2 renderer MeasureText fixed
Fixed annoying warnings when compiling using SFML as platform
SFML2 accelerator (copy and paste) fix
SFML fix for dragging windows outside the rendering region
Replaced Gwen::Event::Packet with void* and added methods for global callbacks
Merge pull request #69 from Wizzard033/master

SFML and MinGW fixes and more
Fixed DisableResizing so it does not mess up positioning of children