Fixed awesome mistake in Math::TypeTraits.

Epsilon value for integral types should be 1, not 0. Updated
documentation and test to reflect the change.

src/Math/Test/TypeTraitsTest.cpp

@@ -42,8 +42,7 @@ void TypeTraitsTest::equalsFloatingPoint() {
 }
 
 template<class T> void TypeTraitsTest::_equalsIntegral() {
-    QVERIFY(TypeTraits<T>::equals(1, 1+TypeTraits<T>::epsilon()));
+    QVERIFY(!TypeTraits<T>::equals(1, 1+TypeTraits<T>::epsilon()));
-    QVERIFY(!TypeTraits<T>::equals(1, 2));
 }
 
 template<class T> void TypeTraitsTest::_equalsFloatingPoint() {

src/Math/TypeTraits.h

@@ -44,7 +44,8 @@ template<class T> struct TypeTraits {
     /**
      * @brief Epsilon value for fuzzy compare
      *
-     * Returns 0 for integer types and reasonably small value for
+     * Returns minimal difference between numbers to be considered
+     * inequal. Returns 1 for integer types and reasonably small value for
      * floating-point types.
      */
     constexpr inline static T epsilon();
@@ -69,7 +70,7 @@ template<class T> struct TypeTraits {
 
 #ifndef DOXYGEN_GENERATING_OUTPUT
 template<class T> struct _TypeTraitsIntegral {
-    constexpr inline static T epsilon() { return 0; }
+    constexpr inline static T epsilon() { return 1; }
 
     inline constexpr static bool equals(T a, T b) {
         return a == b;