Wsapi 1.6 breaks Orbit and potentially other Lua 5.1 apps...

wsapi.xavante uses coxpcall incorrectly, resulting in errors starting a wsapi-xavante instance.
Also, attempts to run Orbit applications (under Lua 5.1) will fail with the "attempt to yield across metamethod/C-call boundary" error, since the coxpcall versions of pcall and xpcall are necessary (not an issue under Lua 5.2).

This pull request addresses both of these issues.