Add a doxygen documentation.

include/ftxui/README.md

@@ -1,30 +0,0 @@
-# Level of abstractions:
-* Level 0: terminal output.
-* Level 1: ftxui::Screen               
-* Level 2: ftxui::Node
-* Level 3: ftxui::Component
-
-## Level 0: terminal output.
-  This is std::cout. You can send text to it.
-
-## Level 1: ftxui::Screen               
-  A rectangular grid of characters.
-  Use Terminal::ToString() to append its content to the console (level 0).
-
-## Level 2: ftxui::Node
-  A hierarchial set of element.
-  They handle layout and render themself on the screen (level 1)
-  See [elements.hpp](./dom/elements.hpp)
-
-  You can make implement your own.
-
-## Level 3: ftxui::Component
-  A hierarchical set of components.
-  Components store some state and react to events:
-  * keyboard
-  * mouse
-  * terminal event
-    
-  Components renders themself by producing ftxui::Node (Level 2)
-
-  Implement your own!

include/ftxui/screen/string.hpp

@@ -7,6 +7,7 @@
 
 #include <string>
 
+namespace ftxui {
 std::string to_string(const std::wstring& s);
 std::wstring to_wstring(const std::string& s);
 
@@ -19,5 +20,6 @@ int wchar_width(wchar_t);
 int wchar_width_cjk(wchar_t);
 int wstring_width(const std::wstring&);
 int wstring_width_cjk(const std::wstring&);
+}  // namespace ftxui
 
 #endif /* end of include guard: FTXUI_SCREEN_STRING_HPP */