Now cregex "appears" to be included (for backward compatibility)

[Iximiel]

Description

Note

rt-coverage-antibetarmsd fails due to what is being solved here #1166

As what's told in #1175 I'm pushing a couple of commit that should solve the backward compatibility with "absence" of cregex.

In the first two I declare that cregex is there in config.txt (plumed config has cregex) and in PLMD::config::hasCregex()

Target release

I would like my code to appear in release v2.10

Type of contribution

• changes to code or doc authored by PLUMED developers, or additions of code in the core or within the default modules
• changes to a module not authored by you
• new module contribution or edit of a module authored by you

Copyright

• I agree to transfer the copyright of the code I have written to the PLUMED developers or to the author of the code I am modifying.

• the module I added or modified contains a COPYRIGHT file with the correct license information. Code should be released under an open source license. I also used the command cd src && ./header.sh mymodulename in order to make sure the headers of the module are correct.

Tests

• I added a new regtest or modified an existing regtest to validate my changes.
• I verified that all regtests are passed successfully on GitHub Actions.

[Iximiel]

I rebased on the current v2.10 because #1166 is now merged, so the tests should pass

I also added a test to check the "phantom" cregex with a comment that explain why it is there (and ran astyle because I forgot that...)

[carlocamilloni]

I am merging it and then we can reduce the numerical precision of that single failing test

[Iximiel]

I am merging it and then we can reduce the numerical precision of that single failing test

I do no think there is a need to do that: the CI looks like is passing with no problems(apart the usual mac one)