Deprecation warning for Saxon 9.7 or less

[AirQuick]

See #596. This pull request prints a deprecation warning message at compile time if Saxon version is 9.7 or less.

On 9.7:

F:\xspec>bin\xspec.bat tutorial\escape-for-regex.xspec
Saxon script not found, invoking JVM directly instead.

Creating Test Stylesheet...
WARNING: Saxon version 9.7 or less is deprecated. XSpec will stop supporting it in the near future.

Running Tests...
Testing with SAXON HE 9.7.0.21
...

On 9.8 or later:

F:\xspec>bin\xspec.bat tutorial\escape-for-regex.xspec
Saxon script not found, invoking JVM directly instead.

Creating Test Stylesheet...


Running Tests...
Testing with SAXON HE 9.8.0.12
...

Commits

• 719351d implements utility functions to handle version information.
• ec1b334 implements the deprecation warning message.
• ca99bec tests the deprecation warning message.
• 2b859d7 updates a test driver so that a test is skipped on Saxon 9.7 because of its known bug (details: Accept x:description without XSpec namespace prefix #586 (comment)).
• c69aae2 adds Saxon 9.7.0.21 to CI matrix.
  • Travis
  • The line in AppVeyor is commented out because of its slowness. We can enable it when we migrate to a faster CI.

[cirulls]

This looks good to me. I reviewed it by running xspec.sh with Saxon 9.7.0.20 and 9.9.1.5 on my machine and it behaved as you described. I also checked that Travis is now running a matrix with 4 Saxon configuration . Feel free to merge it into master.

[galtm]

@AirQuick : I took a quick look at the code, and I should be able to do a more substantive code review by the end of this week. If you want to merge this in, based on the review by @cirulls , I have no problem with that.

[AirQuick]

Thanks @galtm for the update. No haste for this pull request. I'll just wait for your review.

[AirQuick]

Merged the master into this branch and added Saxon 9.7 to azure-pipelines.yml: Azure

[galtm]

Looks good, and I like that the code has many clear comments.

FYI: For the ant-related files, I can see the gist of what you're doing, but I'm not familiar enough to be able to spot a bug, if there is any.

I left one related comment at 23fc4a8#r35154819

[galtm]

The addition of x:extract-version looks good and defensive.

[AirQuick]

Thanks a lot @galtm!

I'm merging this.