ERC 20 contracts V2

[drinkcoffee]

This PR creates a V2 version of the ERC 20 presets. These new presets provide a cleaner, more consistent API. Original ERC 20 contracts (V1 contracts) are deprecated, but still available.

[openzeppelin-code[bot]]

ERC 20 contracts V2

Generated at commit: 06502613affbe5f5070196319313a1af53f3dd2c

🚨 Report Summary

	Severity Level	Results
Contracts	Critical High Medium Low Note Total	2 1 0 11 27 41
Dependencies	Critical High Medium Low Note Total	0 0 0 0 0 0

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For more details view the full report in OpenZeppelin Code Inspector

[drinkcoffee]

This PR is going to be abandoned. Though the new ERC 20 contracts provide some improvements over the existing contracts, this improvement is not substantive enough to warrant an upgrade. The branch will be kept alive, and will be able to be used as the basis for further improvements to the ERC20 contract system.