exceptions: Make Tlv::Error a base class for all packet-processing exceptions

This commit also includes a number of code style fixes.

Change-Id: I44f83915e733b43d5f43b4266902c8262e928d91
Refs: #1528
diff --git a/src/util/io.hpp b/src/util/io.hpp
index ff6852b..0bb929b 100644
--- a/src/util/io.hpp
+++ b/src/util/io.hpp
@@ -76,7 +76,7 @@
     {
       return shared_ptr<T>();
     }
-  catch (Block::Error& e)
+  catch (Tlv::Error& e)
     {
       return shared_ptr<T>();
     }
@@ -134,7 +134,7 @@
     {
       throw Error(e.what());
     }
-  catch (Block::Error& e)
+  catch (Tlv::Error& e)
     {
       throw Error(e.what());
     }