Update to the newer spec

[lifthrasiir]

Notch will release the newer spec soon (the draft is available here), so the stdlib has to be updated to match with that spec.

Major changes for stdlib:

• PUSH and POP has been merged (for now), bulk memory operation abusing SP won't work as is.
• Also the evaluation order of operands has been swapped. Combined with the merger of PUSH and POP this will break almost every code that abuses SP.
• We now have signed operations. Maybe useful for some cases (given that -1 is available for operands).
• SP-relative addressing is available, and it does not cost an additional cycle (in the current spec at least). The affects of this change are to be determined of course.
• Literal as the first operand to get unbranched comparison is not gone, but now slightly inefficient for some cases (no short literal allowed).
• Trivial assembler changes. (Don't think s/\<O\>/EX/g will work, though)

[Blecki]

Merger of PUSH and POP: I was entirely unaware of this. The only time, however, when it made sense to use 'POP' as the first operand in a basic operation was doing comparisons, so this should hopefully not be much of an issue. Does anyone know what 'PICK' is supposed to do?

SP relative addressing : The benefits of this are dependent on the calling convention(s) we choose.

[lifthrasiir]

@Blecki: PICK n is an SP-based addressing. On the other hand, I think that a SP-relative addressing would be useful for a few cases only.

[Blecki]

Ah! So it's a mnemonic for SP+n, just as push is for --SP, etc? That makes sense.

As for it's usefulness; those 'few cases' are any time something is stored on the stack. SP+n lets me reference a stack location in no additional cycles. Notice that the most efficient way to reference stack locations without SP+n is that store SP in another register and use relative addressing on that - which DOES cost additional cycles.