Token: Maintain ERC and EIP traits for Token Compatibility

[jochasinga]

What
Keeping up with the Ethereum technical standard by maintaining equivalent Rust traits in the program library.

Why
Solana has several advantages over Ethereum. By maintaining ERC and EIP API it can be easier for Ethereum
developers to transition to Solana.

Additionally, security token standards such as

EIP 1400: Security Token Standard
EIP 1410: Partially Fungible Token Standard

can be a pathway to a well-implemented #966 (vesting contract feature request) as well as a more sustainable adoption of Solana as security token infrastructure since it is already equipped for uses in exchanges.

How
For starters, keeping a Rust trait like:

trait ERC20 {
        // Optional methods                                                                        

        // fn name(&self) -> String;                                                               
	// fn symbol(&self) -> String;                                                             
        // fn decimals(&self) -> u8;                                                               

        fn total_supply(&self) -> usize;

        fn balance_of(address: &Pubkey) -> usize;

	fn transfer(to: &Pubkey, value: usize) -> Result<(), Option<&str>>;

	fn transfer_from(from: &Pubkey, to: &Pubkey, value: usize) -> Result<(), Option<&str>>;

	fn approve(spender: &Pubkey, value: usize) -> Result<(), Option<&str>>;

	fn allowance(owner: &Pubkey, spender: &Pubkey) -> usize;
}

This can be added as an additional module of the program library with ease.