Port validated integ from TaylorModels

[aa25desh]

Closes #611.

[mforets]

Reachability.solve_continuous: Error During Test at /home/travis/build/JuliaReach/Reachability.jl/test/Reachability/alltests.jl:2
  Got exception outside of a @test
  LoadError: UndefVarError: get_numvars not defined

-> the appropriate using is missing, in this case using TaylorSeries: get_numvars.

[mforets]

Please add TaylorIntegration 0.4.1 in the REQUIRE file, in order to fix the warning:

┌ Warning: Package Reachability does not have TaylorIntegration in its dependencies:
│ - If you have Reachability checked out for development and have
│   added TaylorIntegration as a dependency but haven't updated your primary
│   environment's manifest file, try `Pkg.resolve()`.
│ - Otherwise you may need to report an issue with Reachability
└ Loading TaylorIntegration into Reachability from project dependency, future warnings for Reachability are suppressed.

[schillic]

It is better to do info("...") instead to use the logger.

[schillic]

Could you remove the commented code in this file?

[mforets]

Yes. I'd like to make that and in general use our guidelines https://github.com/JuliaReach/JuliaReachDevDocs/

[mforets]

Thanks for the contribution!

This code is a replacement of TaylorModels.validated_integ so we need to add the copyright string, i think it's ok to add it in the same reach.jl file.

The test uses the tests for TMJets so it looks good. Also note that the build error reported in current master is not showing up (i cannot reproduce it either in my machine). Note, however, that a new warning is shown, about update! function. We can investigate it in a new issue.

In a subsequent PR we'll add early termination with invariant intersection.