The introduction of c_map{} and c_map_pair{} unnecessarily broke the
alphabetical order of Core Erlang records. They were probably placed
at the end of the file so as to use other records as types. There is
really no need for this since 'cerl' contains appropriate definitions
of types that can be used for this purpose.

While at it, a type declaration to the c_binary{} definition was added.

Not only variables are allowed as arguments, the name should reflect that.

Change cerl Map argument interface
 * cerl:map_arg/1 is more suitable then cerl:map_val/1 in this case.

Reject all expressions that are known to fail.
Emit 'badarg' for those expressions.

Ex.

    []#{ a => 1}

Is not a valid map update expression.

Simplify compiler internals and parsing of core format.