array multiplication is removed in 0.17
`@splat(0)` pattern works in both 0.16 and 0.17

There was an additional pop() on the bitlib open that was causing issues
when enabling apicheck in luajit. This is only needed in Lua 5.2

Also fixed bad logic on openVector.

Closes natecraddock#212

When attempting to use a Ziglua function that is not supported for the
target Lua version, the error message is now much more clear.

Before
error: root source file struct 'lua_all' has no member named 'lua_cpcall'

After
error: Lua.cProtectedCall() is not supported in Lua 5.5

Also cleans up documentation comments.

Closes natecraddock#210