Change the SWIG wrappers to stop directly casting SB object to SWIG objects,...

Change the SWIG wrappers to stop directly casting SB object to SWIG objects, and instead use a safer type-checked API (thanks templates)
Any time a SWIG wrapper needs a PyObject for an SB object, it now should call into SBTypeToSWIGWrapper<SBType>(SBType*)
If you try to use it on an SBType for which there is not an implementation yet, LLDB will fail to link - just add your specialization to python-swigsafecast.swig and rebuild

This is the first step in simplifying our SWIG Wrapper layer

llvm-svn: 184580