Remove Mauve tests See previous commit for explanation.

Make stx:libjava tests to compile using JDK 11 This commit fixes some test to compile using JDK 11 and those that cannot be fixed it removes (with regrets). The reason is that it is becoming increasingly difficult to maintain systems with JDK 7 for Smalltalk/X and JDK 11 for the rest. Most importantly, Jenkins now requires JDK 11 (which is reasonable requirement). On top of that, stx:libjava is not being developed in years, it is lagging behind Java development and as such, it is kept just a reminiscent of past that is becoming a drag. And this commit is just makeing it a bit less of a drag.

Test for different methods in `ProjectDefinition >> #postLoadJavaHook` This commit just changes the clumsy test for compiled class libraries to use multiple different methods. `#classNamesAndAttributes` may be missing in (pure) Pharo `PackageManifests`. `#mandatoryPreRequisites` may be missing in some old project definitions created before (single) `#preRequisites` have been split to `#mandatoryPreRequisites` and `#requiredPreRequisites`. Sigh.

Implement `java/util/zip/ZipFile.getManifestNum(J)I` native ...as this is needed by recent OpenJDK 7 (Zulu 7)

Skip `JavaClassReloaderTests >> #test_concurrency_01` ...since is is known to often fail on heavily loaded systems. See issue #306 [1] for more details. [1]: https://swing.fit.cvut.cz/projects/stx-jv/ticket/306

Improve "decompiling" of native methods Native methods are standard Smalltalk methods with smalltalk bytecode. This commit fixes `JavaMethod >> #decompileOn:` to print Smalltalk bytecode.

Improve error message when generic signature cannot be retrieved

Fix details stack trace printing for `JavaContext`s Java methods use Java's variable table to describe methods variables rather than St/X's own debug info. Therefore, `JavaContext >> #argAndVarNames` must be implemented differently. Another fix was needed for `JavaNativeMethod`. Java natives are ordinary smalltalk methods so their activations use (Smalltalk) `Context` and therefore for `Context >> argAndVarNames` to work one must implement `JavaNativeMethod >> dbgVariables`. This commit does all that.

Merge

Fix `JavaRelease` for Zulu 7 and Zulu 8 Recent version of Zulu 7 and Zulu 8 on Debian changed directory names so none of them was currectly auto-detected. This commit adds new paths to fix this issue.