Gas Optimizations

[code423n4]

G-01:

use uint256 for best gas saving
ClearingHouse.sol L#17,18,19,20
MarginAccount.sol L#47

G-02:

uint256 instead of bool
ClearingHouse.sol L#79,250

G-04:

Prefix increments are cheaper than postfix increments.
Further more, using unchecked {++x} is even more gas efficient, and the gas saving accumulates every iteration and can make a real change
ClearingHouse.sol L#122,130,170,194,251,263,278
MarginAccount.sol L#331,373,521

G-05:

immutable instead of constant
MarginAccount.sol L#34,15,

G-06:

use calldata instead of memory

G-07:

use memory instead of storage

G-03:

bytes32 instead of string

[atvanguard]

G-05 is a good suggestioin