Add null? function to lang.
Add typesigged inlineable versions of first, rest, and empty.
Add Seq alias for IPharenSeq.

This is mainly to be used as a shortcut for type annotations.
Correctly extract parameter name from Annotation for tail-rec funcs.
Avoid inlining tail recursive functions.

Instead of getting inlined the compiler simply uses the name of the *fun* in question.

This can be used for performance optimizations by taking advantage of functions which *are* inlined in the original implementation of the tail recursive function.