Enables/Disables Unicode keyboard translation.
To obtain the character codes corresponding to received keyboard events, +Unicode translation must first be turned on using this function. The +translation incurs a slight overhead for each keyboard event and is therefore +disabled by default. For each subsequently received key down event, the +unicode member of the +SDL_keysym structure +will then contain the corresponding character code, or zero for keysyms that do +not correspond to any character code.
A value of 1 for enable enables Unicode translation; +0 disables it, and -1 leaves it unchanged (useful for querying the current +translation mode).
Note that only key press events will be translated, not release events.