Changed project config for lib build
Fix dangling pointer bug in JsonRpc::invoke()

The callback parameter to invoke was a raw pointer, no way to ensure
that it won't get used after deletion (and no way to unregister the
callback.)

Changed it to an std::weak_ptr. Only the weak_ptr is stored, so if a
response is received after deletion the callback will not be invoked.
Update rules file
Merge remote-tracking branch 'origin/winveyor'

Conflicts:
	win/vcxproj/jsonrpc/jsonrpc.vcxproj
Merge remote-tracking branch 'origin/master' into improve_scons_a

Conflicts:
	debian/rules