GROOVY-5571: Missing or wrong osgi headers since 2.0-rc1 (remove accidental references to some bootstrap classes)
GROOVY-5587: Incomplete type inference for entrySet()
   - GROOVY-5594 Type checker doesn't infer property type if coming from a generified getter
   - GROOVY-5595 Type checker doesn't fully infer Map.Entry type
GROOVY-5597: Add a label lookup feature to @ASTTest
   - Improved unit test for LoopsSTCTest using that feature
GROOVY-5587: Fix generics types mixed up because type doesn't use getPlainNodeReference
Revert "GROOVY-5571: Missing or wrong osgi headers since 2.0-rc1 (remove accidental references to some bootstrap classes)"

This reverts commit 3ebf9e11916f8dafd448fab79fc72f149781077b.
The GroovyClassLoaderTest actually modifies the source encoding value of CompilerConfiguration.DEFAULT (and doesn't reset it).
On systems not using UTF-8 as the default "file.encoding", it made the CompilerConfigurationTest actually fail as the default encoding of CompilerConfiguration wasn't the same anymore as the platform one.
GROOVY-5599: Fix type checker returning curious errors if a variable using generics was assigned to null
GROOVY-5569: Incorrect type checking of generics of a call argument
Similarly to GROOVY-5248 (call site caching missing null check), add a receiver null check to avoid NPEs under certain circumstances (build failures on Mac OS X for CategoryTest#testNullReceiverChangeForPOJO and ListTest#testFlattenListWithSuppliedClosure)
GROOVY-5588: correct type for array get
GROOVY-5586: @ToString doesn't set implicitThis to false when receiver is not "this"
GROOVY-5571: Missing or wrong osgi headers since 2.0-rc1 (remove accidental references to some bootstrap classes - 2nd attempt)
tweak timing params to increase build success on very slow machines (e.g. codehaus bamboo server)
GROOVY-5593: A module using an incompatible class format version would prevent groovy from running
Set a different test configuration if we detect we are running on CI server
tweak timing params to increase build success on very slow machines (e.g. codehaus bamboo server)
Merge remote-tracking branch 'origin/master'
Try a different key for the bamboo detection
Yet another attempt to detect bamboo
tweak distSrc task dependencies