Fix ROUND=2, add BACKSPACE/TAB/ENTER key constants

Author: pepc84

src/Processing.h

@@ -1172,6 +1172,9 @@ static constexpr char ENTER     = 10;   // PC/Unix enter key
 #ifdef DELETE
 #  undef DELETE
 #endif
+static constexpr int BACKSPACE = 8;
+static constexpr int TAB       = 9;
+static constexpr int ENTER     = 10;
 static constexpr int RETURN    = 13;   // Mac return key (same key as ENTER on most systems)
 static constexpr int ESC       = 27;
 static constexpr int DELETE    = 127;
@@ -1190,7 +1193,7 @@ static constexpr int CORNERS     = 1;
 static constexpr int RADIUS      = 2;
 
 // Stroke caps and joins
-static constexpr int ROUND   = 10;
+static constexpr int ROUND   = 2;
 static constexpr int SQUARE  = 1;
 static constexpr int PROJECT = 4;
 static constexpr int MITER   = 8;