Consistency cleanup: renamed "getPkg()" to "getPackage()".

.../com/oracle/truffle/r/test/packages/analyzer/Problem.java

...cle/truffle/r/test/packages/analyzer/RPackageTestRun.java

...kages/analyzer/detectors/InstallationProblemDetector.java

...le/r/test/packages/analyzer/detectors/RErrorDetector.java

.../r/test/packages/analyzer/detectors/SegfaultDetector.java

...truffle/r/test/packages/analyzer/dump/AbstractDumper.java

...ruffle/r/test/packages/analyzer/parser/LogFileParser.java