Clarify self-referential local functions

The current language used implies that `local function f() ... end`
does not allow f to invoke itself.  This has been clarified via the
addition of an example of a local function that may *not* invoke
itself.
Add another example of function call without parens

Function calls using a table literal as its sole parameter
may also omit parentheses
Use local variables for function examples

Currently, the example functions create variables in global
scope.
Merge pull request #306 from hoelzro/master

A few clarifications for the Lua documentation