Make HostManager a member of mudlet (the class).

This approach, rather than using a global singleton, makes it so that its
lifetime is better understood.
Merge branch 'release_31' into development

Make HostManager a member of mudlet (the class).
Fix deletion of the various types of user created objects. This probably doesn't fix all instances, but it should be much closer.
Remove dead stats code from AliasUnit.
casts
get url
TMap::vertex
Avoid macro max/min with parentheses.
Remove luazip lua bindings on windows.
Boost includes <hash_set> on GCC unless BOOST_NO_HASH is defined which causes a deprecation warning on newer versions of GCC.
Eliminate some warnings by using negative values for constants in ctelnet.
Fix leaks in XMLimport.
Fix leaks of dlgMapper.
Delete QTimer sooner.
Change the get*Unit() functions in Host to return references rather than pointers.
Add QT_NO_KEYWORDS to the build options.
Move TMatchState from TMatchState.h to TTrigger.cpp.
Remove unnecessary casts.
Use const T& more consistently throughout.
Make it build.