Compatibility fixes to enable Platform to build with the latest Autowiring without modifications

- Adding operator bool to auto_in, marking it as deprecated and setting it to trivially return
- auto_in is now based on a shared pointer, without loss of generality
- AutoFilter instances should be able to accept undefined types as inputs
- Argument types are identified by the auto_id metatype rather than directly by their type
- It should be possible to inject an AutoFilter even if _none_ of its arguments are defined
Merge remote-tracking branch 'origin/develop' into fix-backwardscompat

Conflicts:
	autowiring/AutoPacket.h
Fixing Linux build
Merge remote-tracking branch 'origin/develop' into fix-backwardscompat
Use auto_id when constructing a SharedPointerSlot in order to avoid issues with forward-declared typeid
Merge pull request #262 from leapmotion/fix-backwardscompat

Compatibility fixes to enable Platform to build with the latest Autowiring without modifications