C/C++ Standard Lib for contracts (part 1)

test system contract

Reduce wasm table vmem usage

(pending checktime fixes at some point in the future)

Previously, a 68GB virtual memory map was created per wasm (contract) instance. This eats up the virtual memory space exceptionally quick.

Now, only allocate 12KB per wasm/contract instance. This is enough for 1024 table elements which is hopefully plenty. The side effect is that every indirect function call now has an additional runtime check on its value (checking if it is less than 1024). This seems like an acceptable tradeoff.

Also I have removed the 4GB alignment for the table and replaced it with 4KB. I wasn’t finding any benefit to that 4GB alignment. The generated x86_64 code was simply in the form of *8(%base, %index) so I probably don’t even need 4KB.

Place some of the wasm_constraints in constexpr variables that can be referred to from elsewhere

GCC compatibility.

#1222, jira-536, import changes from the dawn 2.x based branch.

Travis tests

Identity contract (part 2)