investigate replace in go.mod instead of renaming all imports

[liamsi]

Can we avoid merge conflicts and decrease maintenance costs for updating to upstream (tendermint) master by using replace?

• https://golang.org/ref/mod#go
• https://github.com/golang/go/wiki/Modules#when-should-i-use-the-replace-directive

[liamsi]

One observation is that tendermint (and hence ll-core) uses some internal package(s) (e.g. github.com/tendermint/tendermint/tools/tm-signer-harness/internal or github.com/tendermint/tendermint/crypto/internal/benchmarking) which doesn't seem to work well with the replace directive.
E.g.,

package github.com/lazyledger/lazyledger-core/tools/tm-signer-harness
        tools/tm-signer-harness/main.go:14:2: use of internal package github.com/tendermint/tendermint/tools/tm-signer-harness/internal not allowed

We might be able to work around this though.

But even if I remove all packages (it's mostly test packages, eg. the tm-signer-harness and the bench_tests for the sig libs), there are still a lot of errors. I'll push a branch with my findings so far.

[liamsi]

https://github.com/lazyledger/lazyledger-core/tree/ismail/experiment_with_replace

[liamsi]

TBH, I don't think replace is meant to be used like this (replace the module that you are defining), only to replace dependencies (which could be forks).

[liamsi]

Also, to quote a go core dev:

replace is intended to support local development, not permanent forks: if you need to permanently fork a dependency, your fork must have its own, unique import path.

[liamsi]

Closing for now.