libui bindings for Euphoria

• Wrapper code is complete; new features will be added as they arrive in libui.
• Testing is incomplete. More examples are welcome.

This wrapper should be stable but keep in mind that libui is still in alpha status.

• Added DEBUG output to define_c_func/proc
• Added uiControlVerifySetParent()
• Added uiControlEnabledToUser()
• Added uiUserBugCannotSetParentOnToplevel()
• Added blurb about position routines to comments
• Added test for -1 in event handler assignment
• Removed missing uiDraw functions

• Added new position functions
• Added more uiDrawBrush functions
• Removed old position functions

• Added uiFormDelete()
• Added uiProgressBarValue()
• Added uiMainSteps()
• Added uiNewVerticalSeparator()
• Added window position functions
• Added window borderless functions
• Added window fullscreen functions
• Added Window content size functions

• Added more examples
• Wrapped uiGrid control
• Changed call_back() lines to use CDECL
• Fixed memory allocation in uiDrawTextLayoutExtents

• Wrapped more draw functions
• Wrapped new uiForm control

• Wrapped more draw functions

• Wrapped more controls
• Wrapped draw functions
• Changed string functions to call uiFreeText()
• Completed controlgallery.ex example

• Initial commit
• Wrapped most controls
• Created controlgallery.ex example

A keen observer might notice the seemingly unorthodox C wrapper code used in ui.e. What I've done here, is use a map to provide string lookups for function names instead of using constants. This is an experiment in providing a cleaner C library wrapper. The calls to define_c_func/proc look a lot more like attributes used in C# or VB.NET. I have not compared this method to using constants, so I'm not sure if or by how much this might be slower.

constant _uiNewWindow = define_c_func( libui, "uiNewWindow", {C_POINTER,C_INT,C_INT,C_INT}, C_POINTER )
public function uiNewWindow( sequence title, atom width, atom height, atom hasMenubar )
    return c_func( _uiNewWindow, {allocate_string(title,1),width,height,hasMenubar} )
end function

define_c_func( libui, "uiNewWindow", {C_POINTER,C_INT,C_INT,C_INT}, C_POINTER )
public function uiNewWindow( sequence title, atom width, atom height, atom hasMenubar )
    return c_func( "uiNewWindow", {allocate_string(title,1),width,height,hasMenubar} )
end function