Fixes according to reviewer's remarks

changelog.d/170.feature.rst

@@ -0,0 +1 @@
+* Add pretty string representation for matchers objects

src/hamcrest/core/string_description.py

@@ -1,4 +1,5 @@
 from hamcrest.core.selfdescribing import SelfDescribing
+from textwrap import shorten
 
 from .base_description import BaseDescription
 
@@ -32,8 +33,8 @@ def __str__(self) -> str:
         return self.out
 
     def __repr__(self) -> str:
-        """Returns the description."""
-        return self.out
+        """Returns the object string representation."""
+        return "<{0}({1})>".format(self.__class__.__name__, shorten(self.out, 60, placeholder="..."))
 
     def append(self, string: str) -> None:
         self.out += str(string)