changed inspect for DenseMatrix

Author: rajithv

lib/symengine.rb

@@ -41,3 +41,4 @@ def Function(n)
 require 'symengine/complex_double'
 require 'symengine/undef_function'
 require 'symengine/matrix_base'
+require 'symengine/dense_matrix'

lib/symengine/dense_matrix.rb

@@ -0,0 +1,7 @@
+module SymEngine
+  class MatrixBase
+    def inspect
+      "#<#{self.class}(#{rows}x#{cols})>"
+    end
+  end
+end