Add a new type and data structure to LPC. Lightweight objects combine
properties from structs (small memory footprint, automatic lifetime
management) and objects (capsulation, functions).
(Implements #688)
When lfun or variable objects are created, we need to make sure,
the indices are adjusted if a replace_program() is in progress.
Just like closures we create a protector structure that will be
processed after the replace_program().
In Python the representation of an LPC object offers an attribute
variables, that contains all variables of that object with some
information about it and an attribute to change its value.
In Python the representation of an LPC object offers an attribute
functions, that contains all visible functions of that object
with some information about that function and the call operator.
