This commit consist a series of fixes to make the reach the main
goal of the commit:
* Fix the 'MakeNodeFromExprs' behavior so it returns a pointer
to a node and if the number of input exprs is zero then nil.
* Fix all the eval loop to return immediately in case of any error
duh!
* Add a `errtype` field to `Error` with an `ErrType` enum type
that indicates the type of the error, the type being syntax,
semantic and runtime error at the moment.
* Rename some of the Error functions to match the error type. For
Exapmle `MakeSyntaxError` and `MakeSemanticError`
Added the support for normal macro (in compare to reader macros and
other types) expansion with out quasiquote support. The quasiquote
will be added as a recursive macro itself.
Sameer Rahmani