Use ign-math SemanticVersion in LocalCache.cc

[osrf-migration]

Original report (archived issue) by Nate Koenig (Bitbucket: Nathan Koenig).

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Summary

We can use SemanticVersioning here: https://osrf-migration.github.io/ignition-gh-pages/#!/ignitionrobotics/ign-fuel-tools/pull-requests/82/ready-integration-with-ign-gazebo/activity#comment-89119795

Motivation

The SemanticVersion class contains logic for properly comparing version numbers. This will add a dependency on ign-math.

[osrf-migration]

Original comment by Louise Poubel (Bitbucket: chapulina, GitHub: chapulina).

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Note that we already have an indirect dependency on libignition-math6 through libignition-common3, and for some reason pipelines is explicitly installing libignition-math4-dev

[osrf-migration]

Original comment by Steve Peters (Bitbucket: Steven Peters, GitHub: scpeters).

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that sounds like a bug in the pipeline. I would change the math4 to math6

[osrf-migration]

Original comment by Steve Peters (Bitbucket: Steven Peters, GitHub: scpeters).

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I don't think it's a big problem to add an explicit dependency on ignition-math since it's already being used implicitly anyway