Prevent reentrancy from changing the delegate list. Fixes #651
Fix namespace.
Remove weak event managers on Net45.
Add WeakHandlerList that can be cloned when necessary.
Merge pull request #672 from reactiveui/disable-weakeventmanager-for-wpf

Disable WeakEventManager for WPF
Mark these as preserve or we'll crash on startup on full link
Merge remote-tracking branch 'origin/pr/671'
Version bump to 6.0.1
Enable Weak Reference Manager in WinForms
Bump versions of various packages