@sueloverso, here are the changes that largely limit passing WT_CONNECTION_IMPL to the __wt_connection_XXX functions.

I ended up searching include/extern.h for functions that took WT_CONNECTION_IMPL as an argument, and searching for all uses of WT_CONNECTION_IMPL.default_session, and switching to passing WT_SESSION_IMPL in the cases where I thought it made sense to do so.

Please review and merge if/when you think it's right!