Merge pull request #141 from lawrenceakka/topology-fixes

Fixes to new topology code. I'll merge myself since this changes litre except making things rather faster!
Much quicker discovery

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extra : rebase_source : 30353b4547075986a908e7a9194097e41fb54456
line too long error

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extra : rebase_source : 364ca891e5c1b397551730fbcd672ffde675a0b2
Shared zgs caching

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extra : rebase_source : 9ac288e27f685c5887a44d36f7dcf5922b787564
Lint

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extra : rebase_source : 5c1fcd707408bafe5196c6782ba75d747459bcf4
Revise examples in Readme

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extra : rebase_source : dffb16590ef6b20ece4410c89855fda89d26552e
Typo in README