Add `eth.BlockSpecifier` for EIP-1898 Support about go-ethlibs HOT 3 CLOSED

We're generally ok with breaking compatibility in this module for now, especially if it makes the module itself easier to use, so at this point I still consider this module "v0" with respect to compatibility promises.

For example I'd really like to implement #17 and move away from defining per-RPC methods on node.Client; it'd be a sizable change to the interface to start, but would mean that new RPCs can be added going forward without any changes to implementers of the Client interface in other packages.

from go-ethlibs.

@ryanschneider are we concerned about preserving backwards compatibility?

E.g. changing the definition of BlockNumberOrTag from

type BlockNumberOrTag struct {
	number Quantity
	tag    string
}

to

type BlockNumberOrTag struct {
	number Quantity
	tag    Tag
}

might break existing code (outside go-ethlibs)?

from go-ethlibs.

Merged EIP-1898 Support into master.

from go-ethlibs.