Add an ERC20.transfer wrapper

[smol-ninja]

@razgraf proposed an idea to include a token transfer function (an ERC20.transfer wrapper) in the contract. The UI can then use batch for transfer + create-stream actions.

The goal is to enable new use cases such as "payroll setup + initial bonus" where sender wants to transfer some tokens directly to the recipient while creating the stream.

RFC @sablier-labs/solidity.

[PaulRBerg]

Interesting idea, but how this be different from allowing Flow streams to have a variable start time, @razgraf?

Is the point to make the initial bonus arbitrary, i.e., NOT a function of RPS/ time passed?

[razgraf]

Technically, it shouldn't differ. But in terms of logic and UX:

• amount wouldn't be a function of RPS, as you preempted, meaning it can be independent of it
• the stream itself will not have to be backdated
  • e.g. if I want to send an initial signing bonus of 1000$ but then grant 500$/month, the start date would have to be 2 months ago which could be confusing in the UI

[PaulRBerg]

Alright, I'm in favor of this, let's implement it (unless @andreivladbrg finds any issues with it).

[andreivladbrg]

I really like the idea! 👌

Adding batch was such a great move—it opens the door to these kinds of cool features

[smol-ninja]

Since we all are in agreement, creating the issue now:

• Add an ERC20.transferFrom wrapper #361