Fix case for output of %x and %X
Fix length/1 so it returns single value from metamethod
Change luerl_lib:is_true_value/1 to boolean_value/1

This is a better name as it does return the value as a boolean.
Add concat as callable erlang function
First version of require and package module

This is an alpha version. It works but is incomplete and data is
unprotected. Still can't reconcile this execution with documentation.