required by an upgrade of autopep8

Allow retrieve or disable a ToolHandle in one line:
```cpp
m_mcTool.retrieve( DisableTool{m_MCFlag || m_feelingLucky} );
```

was broken by !470

Right now, the Gaudi::Property<T> code assumes that the type T is
default-constructible. But it only uses this assumption when a value of
type T is parsed from a string. With a couple of modifications to the
string parsing function, Gaudi::Property<T> can work with
copy-constructible types as well.

See merge request gaudi/Gaudi!582

Added a new event loop manager for HLT like usage, that is very simple and very fast scheduling (mr !537)

Closes #1

Fixed use of zlib

See merge request gaudi/Gaudi!553