Supporting Intrinsic `LOAD` and `STORE` 64 bit values

[zrthxn]

I was interested in contributing to this, so I figured I should ask how you're thinking this should be implemented. Mainly, should the size of the value to be read be an input (like 8, 16, 32, 64 bit) OR should it just have intrinsic support for 64 bit values and then have standard library macros provide support for other sizes?

If its only 64 bit then it can probably just be done with

pop rax
xor rbx, rbx
mov rbx, [rax] ;; Instead of mov bl, [rax]
push rbx

[zrthxn]

So for now I've tested with just 64 bit LOAD and STORE. The operators are rather unimaginative, ,64 and .64

// Test 1000...0001 (64 bit)
mem 1 63 shl 
1 + .64
mem ,64 print

// Test UINT64_MAX
mem 18446744073709551615 .64 
mem ,64 print

[rexim]

@zrthxn this looks good for now. In the future I plan to approach the size of load/store slightly differently, but for now it's alright.

[zrthxn]

@rexim Do you want to use different operators...? Maybe .64 and ,64 aren't the best

[rexim]

@zrthxn nah, .64 and ,64 are alright. I don't really care much about specific names since they always can be changed later while we are in active development phase and nothing is stabilized yet.

[zrthxn]

Okay then #54 is waiting approval :)