Removed gtk and implemented Windows API file dialog

- Removed all code and references to gtk file dialog because it was
requiring a GtkWindow object to initialize the file dialog
- Changed to Windows API for implementing 'Open' file dialog
- It is now opening and returning a string, but the string is not being
captured yet for the file streaming
NOTE: Had to enable 'Use Multi-Byte Character Set' (Debug and Release)
for this to work
(http://social.msdn.microsoft.com/forums/en-US/vclanguage/thread/c1b08c0a-a803-41c3-ac8c-84eba3be1ddb/)
[Alt-F7 to open -> Configuration Properties>General].  Otherwise, got an
error similar to the one from that page "cannot convert parameter 1 from
'const char [12]' to 'LPCTSTR'"
- Used this example
(http://msdn.microsoft.com/en-us/library/ms646829(VS.85).aspx#open_file)
- and this example (http://www.libsdl.org/cgi/docwiki.cgi/SDL_GetWMInfo)