add api FIFO based character input. (#1012)

* add api FIFO based character input.

* rename input character functions

* replace tab to space x4 #1012

src/raylib.h

@@ -978,6 +978,9 @@ RLAPI bool IsKeyUp(int key);                                  // Detect if a key
 RLAPI int GetKeyPressed(void);                                // Get latest key pressed
 RLAPI void SetExitKey(int key);                               // Set a custom key to exit program (default is ESC)
 
+RLAPI bool IsCharAvailable();                                 // Check if input character exists at least one in the internal input character stream. The characters are produced by the operating system text input system.
+RLAPI unsigned int GetNextChar();                             // Pull a input character from the the internal input character stream
+
 // Input-related functions: gamepads
 RLAPI bool IsGamepadAvailable(int gamepad);                   // Detect if a gamepad is available
 RLAPI bool IsGamepadName(int gamepad, const char *name);      // Check gamepad name (if available)