Improved comments on Numbers API.
Added Natives API.

The API has not been implemented yet.
Implemented natives API.

However correct marking will not work yet.
Added environment API.
Added environment and symbol APIs.
Added native functions to the mix.
Added compiler extensions and number arithmetic.
Added + compilation function.

Also added arithmetic functions and some examples.
Added multiplication operator.
Added pr and prn natives, and fixed ncall instruction dump.
Added subtract compiler function.
Added subtract and divide compiler functions.

Added NE_CHECK macro.
Added JP and CHECK instructions and predicates.
Fixed the bug where natives were loaded after scripts were run.
Fixed crash bugs in NE_IS_INTEGER etc macros.
Changed test-table.n to run code now with prn.
Constant duplicates are removed during compilation.
Started work on lambda compilation.